Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives

Zi, Cheng-Ting; Liu, Zhen-Hua; Li, Gen-Tao; Li, Yan; Zhou, Jun; Ding, Zhong-Tao; Hu, Jiang-Miao; Jiang, Zi-Hua

doi:10.3390/molecules20023255

Open AccessArticle

Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives

¹

Key Laboratory of Medicinal Chemistry for Nature Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming 650091, China

²

State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China

³

Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada

^*

Authors to whom correspondence should be addressed.

Molecules 2015, 20(2), 3255-3280; https://doi.org/10.3390/molecules20023255

Submission received: 11 January 2015 / Accepted: 4 February 2015 / Published: 16 February 2015

(This article belongs to the Section Medicinal Chemistry)

Download

Browse Figures

Versions Notes

Abstract

:

A series of novel perbutyrylated glycosides of 4β-triazolopodophyllotoxin derivatives were synthesized by utilizing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Evaluation of cytotoxicity against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, SW480) using the MTT assay shows that some of these glycosylated derivatives have good anticancer activity. Among the synthesized compounds, compound 21a shows the highest activity, with IC₅₀ values ranging from 0.49 to 6.70 μM, which is more potent than the control drugs etoposide and cisplatin. Compound 21a is characterized by a perbutyrylated α-D(+)-galactosyl residue, the absence of an additional linking spacer between the sugar residue and the triazole ring, as well as a 4'-OH group on the E ring of the podophyllotoxin scaffold.

Keywords:

podophyllotoxin; glycosylated; 4β-triazole; CuAAC reaction; antitumor; synthesis

Graphical Abstract

1. Introduction

Podophyllotoxin (1, Figure 1), a well-known naturally occurring aryltetralin lignan extracted from the roots of Podophyllun peltatum, has been known to inhibit the assembly of tubulin into microtubules through tubulin binding, but the high toxicity of podophyllotoxin has limited its application as a drug in cancer chemotherapy [1,2,3,4]. The potent anticancer activity of 1 has led to extensive structural modifications for the discovery and development of new anticancer agents. Etoposide (2, Figure 1) [5] is a semisynthetic glucosidic cyclic acetal of podophyllotoxin which is in clinical use as an antineoplastic agent against various cancers, including small-cell lung cancer, non-Hodgkin’s lymphoma, leukemia, Kaposi’s sarcoma, neuroblastoma and soft tissue sarcoma [3,6,7,8,9,10,11,12]. However, the therapeutic use of 2 is often overcome by the problems of drug resistance, myelo-suppression and poor oral solubility. In order to overcome drug resistance and improve topoisomerase II inhibition, various structure modifications of podophyllotoxin have been made [13,14], novel dimeric podophyllotoxins obtained by condensation of thiocolchicine and/or podophyllotoxin with six different dicarboxylic acids, having a marked ability to inhibit the polymerization of tubulin in vitro and the spacer unit was found to have a significant effect on biological activity [15]. According to structure-activity relationship (SAR) studies, 4^′-demethylation, 4-epimerization, trans-lactone D ring with 2α, 3β configuration and free rotation of ring E were essential to maintain the anticancer activity of podophyllotoxin derivatives as topoisomerase-II inhibitors [16,17]. Studies have also demonstrated that substitution at C-4 is tolerable to significant structural diversification.

Figure 1. Structures of podophyllotoxin (1), etoposide (2) and podophyllotoxin derivatives (3).

Traditional cancer chemotherapy is often accompanied by systemic toxicity to the patient, therefore the development of new antitumor drugs with increased selectivity and reduced toxicity is highly desirable. Recently, antibody-drug conjugates (ADCs) that use antibodies to deliver a potent cytotoxic compound selectively to tumor cells were approved for cancer therapy: CD30-targeting brentuximab vedotin for use in Hodgkin lymphoma and anaplastic large cell lymphoma (ALCL), and HER2-targeting ado-trastuzumab emtansine (T-DM1) for use in metastatic breast cancer [18]. Carbon nanomaterials are a source of materials that show unique biological applications for their π-electron cloud and structures. Species such as carbon nanotubes (CNTs), fullerenes, graphenes, carbon nanoparticles, nanodiamonds, carbon nanohorns and carbon nanocaps are common in the formulations of these nanomaterials as biosensors, imaging probes, drug and gene delivery systems, and nanomedicine [19]. By combination with other materials, the nanoarchitectures of nanocarbons can be formed into structures of different dimensions and properties for biological applications, especially cell growth, sensing, and control [20].

In recent years, the preparation of glycoconjugates of small molecule anticancer drugs has become an attractive strategy in order to improve drug efficacy. The clinically widely prescribed anticancer drug etoposide (2) is a β-d-glucopyranoside of 4'-demethylepipodophyllotoxin [21,22,23]. The anticancer activity of other types of podophyllotoxin glycosides, e.g., α-glucopyranoside, α/β-galactopyranoside, α/β-mannopyranoside, etc., has not been well studied. In our previous study [24], we reported 4β-triazole-linked glucose podophyllotoxin conjugates as a new class of antitumor compound; it was found that podophyllotoxin derivatives with a perbutyrylated glucose residue showed high activity. Reported here are the chemical synthesis of a series of perbutyrylated glycosides (D-Gal/D-Man/D-Xyl) of 4β-triazolopodophyllotoxin derivatives (3, Figure 1) conjugated with a specific monosaccharide residue and their in vitro anticancer activity against five human cancer cell lines, including HL-60 (leukemia), SMMC-7721 (hepatoma), A-549 (lung cancer), MCF-7 (breast cancer), and SW480 (colon cancer).

2. Results and Discussion

2.1. Chemical Synthesis

Since the 1,2,3-triazole ring moiety is a widespread functional group in drugs [25,26], the click reaction of copper-catalyzed azide-alkyne cycloaddition (CuAAC) has been widely used to covalently link two molecular fragments between a terminal alkyne and an azide to generate substituted 1,2,3-triazoles [27,28]. To facilitate the coupling of the sugar residue with the podophyllotoxin scaffold, a group of glycosylated terminal alkynes 12a/b–17a/b have been prepared (Scheme 1). Fischer type glycosylation of D(+)-galactose, D(+)-mannose, or D(+)-xylose with propargyl alcohol 4 or its derivative 5 containing three ethyleneglycol units [29] in the presence of H₂SO₄-silica as a catalyst afforded the desired propargyl glycosides 6–11 as α/β mixtures in 69%–75% yield [30]. Compounds 6–11 were perbutyrylated with butyric anhydride and pyridine [31] to give the perbutyrylated glycosylated terminal alkynes 12a/b–17a/b, in 89%–96% yield. In each case the α/β mixture was separated to give both the α- and β-anomer in pure form.

Click chemistry involves a terminal alkyne and an azide that undergo a copper-catalyzed [3+2]-cycloaddition to generate a triazole ring [27,32]. There have been numerous reports documenting the best reaction conditions for this cycloaddition reaction [32,33]. It appears that the type of catalyst (copper species), the additive, the solvent, and the reaction time can all affect the yield of this addition reaction. We did a quick screening for the reaction conditions that would work best for our substrates. Thus alkyne 12a was reacted with 4β-azidopodophyllotoxin 18 [24,34] under different reaction conditions to give the 1,2,3-triazole derivative 20a (Scheme 2). The reaction conditions and the respective yields are listed in Table 1.

Scheme 1. Synthesis of glucosylated terminal alkynes.

Reagents and reaction conditions: (i): cat. H₂SO₄-silica, 65 °C, 69%–75%. (ii): n-butyric anhydride, pyridine, 16 h, 0 °C, 89%–96%.

Scheme 2. Click-chemistry strategy for the synthesis of the 1,2,3-triazole derivative 20a.

Table 1. Screening of the reaction condition for the CuAAC reaction between 4β-azido-podophyllotoxin (18) and the glycosylated terminal alkyne (12a).

**Table 1.** Screening of the reaction condition for the CuAAC reaction between 4β-azido-podophyllotoxin (18) and the glycosylated terminal alkyne (**12a**).
Entry	Catalyst	Additive	Solvent	t (h)	Yield (%)
1	CuSO₄·5H₂O	Sodium l-Ascorbate	t-BuOH/H₂O (1:1)	2	70
2	CuSO₄·5H₂O	Sodium l-Ascorbate	t-BuOH/H₂O (1:2)	2	90
3	CuSO₄·5H₂O	Sodium l-Ascorbate	DMF/H₂O (3:1)	2	63
4	CuSO₄·5H₂O	Sodium l-Ascorbate	DMSO/H₂O (1:1)	2	80
5	CuSO₄·5H₂O	Sodium l-Ascorbate	t-BuOH	2	nr ^a
6	Cu(OAc)₂	Sodium l-Ascorbate	t-BuOH/H₂O (1:2)	2	67
7	Cu(OAc)₂	Sodium l-Ascorbate	t-BuOH/H₂O (1:2)	31	87
8	CuI	None	MeCN	12	60
9	CuI	None	t-BuOH/H₂O (1:2)	12	15
10	CuI	None	DMSO/H₂O (9:1)	12	63

Note: ^a nr: no reaction.

As can be seen in Table 1, the reaction occurred with different solvents in the presence of CuSO₄·5H₂O and sodium L-ascorbate within 2 h (Entries 1–4). It is found that t-BuOH/H₂O (1:2) as the solvent provided the highest yield. No transformation occurred in the presence of t-BuOH alone as the solvent (Entry 5). Using the combination of Cu(OAc)₂ and sodium L-ascorbate as the source of Cu(I) species [35], the reaction time can affect the yield significantly (Entries 6,7). In the case of CuI-catalyzed reactions [32,33], the solvent was also found to influence the reaction rate (Entries 8–9); however, the reaction yield was not further improved compared to CuSO₄·5H₂O/sodium L-ascorbate system (Entries 1–4). Subsequently, CuSO₄·5H₂O/sodium L-ascorbate with t-BuOH/H₂O (1:2) as the solvent and the reaction time of 2 h (Entry 2) was chose as the condition for the CuAAC reaction of all substrates reported herein.

The azides 18 and 19 [24,34] were allowed to react with the above terminal alkynes (12a/b–17a/b) in the presence of CuSO₄·5H₂O, sodium ascorbate in t-butyl alcohol and water (1:2) at room temperature to give glycosylated 4β-triazolopodophyllotoxin derivatives 20a/b–31a/b in excellent yield (Scheme 3).

Scheme 3. Click-chemistry strategy for the synthesis of 4β-triazole-podophyllotoxin derivatives.

Reagents and conditions: (i): CuSO₄·5H₂O, sodium ascorbate, t-BuOH-H₂O (1:2), 2 h, rt. 82%–92%.

All the products were characterized by ¹H-NMR, ¹³C-NMR, ESI-MS, and HRESI-MS. In the ¹H-NMR spectra, the formation of the podophyllotoxin triazoles was confirmed by the resonance of the C^5"-H signal (δ7.72–8.33 ppm) of the triazole ring in the aromatic region, which was further supported by two characteristic carbon signals at around 123 ppm and 126 ppm in the ¹³C-NMR spectra. The configuration at the C-4 position for target compounds 20a/b–31a/b was confirmed based on the J_3,4 coupling constant, which is typically < 5.0 Hz for 4β-substituted compounds due to a cis relationship between H-3 and H-4 [36]. ESI-MS and HRESI-MS of all compounds showed the [M+Na]⁺ or [M+H]⁺ adduct as the molecular ion.

Two representative compounds (21a and 26b) were selected for investigation of the chemical stability in aqueous phase in comparison of podophillotoxin (1). The results indicate that compounds 21a and 26b exhibit better chemical stability under the specific conditions (37 °C, pH = 7.0, Figure 2). Obviously, compound 26b is the most stable one, and having the appropriate length of the linking spacer between the sugar and triazole ring and 4'-OCH₃ on the E ring improved the chemical stability of podophillotoxin. These improvements make them much more drug-like than the natural parent podophillotoxin (1), and would be promising for the future further development.

Figure 2. Chemical stability investigation of compounds 1, 21a and 26b.

2.2. Evaluation of Biological Activity

All the perbutyrylated glycosides of 4β-triazole-podophyllotoxin derivatives 20a/b–31a/b were tested for their anticancer activity against five human cancer cell lines, including HL-60 (leukemia), SMMC-7721 (hepatoma), A-549 (lung cancer), MCF-7 (breast cancer), and SW480 (colon cancer). Etoposide (2) and cisplatin were taken as reference compounds. The screening procedure was based on the standard MTT method [37], and the anticancer activity data are presented in Table 2. Among these compounds 21a shows the most active inhibition against all five cancer cell lines tested, with IC₅₀ values ranging from 0.49 to 6.70 μM. Compound 21a displays higher cytotoxic potency than the control drug etoposide (2) against four of the five cancer cell lines tested. Some other compounds also exhibit promising antitumor potency against one or more cancer cell lines. Against the HL-60 cancer cell line, compounds 20a, 24a and 26b demonstrate cytotoxicity with an IC₅₀ below 10 μM. Most of the other compounds display moderate to weak cytotoxicity against all cancer cells tested.

In our previous study on glucosylated podophyllotoxin derivatives linked via a 4β-triazole ring [24], we have shown that the length of the linker between the glucose moiety and the 1,2,3-triazole residue, the substituents on the glucose residue as well as on the 4^′-position of the E ring can significantly affect the anticancer potency of these compounds. Similar structure-activity relationships are also observed for the series of compounds reported here. The present study also shows that different sugar residues conjugated with 4β-triazolopodophyllotoxin also influence the anticancer activity of these compounds. The most active compound (21a) contains a D-galactose residue, and all other compounds containing a D-mannose or D-xylose residue (24a/b–31a/b) display moderate to weak activity. The majority of the compounds with an α-glycosdic linkage are more active than those with a β-linkage (20a vs. 20b, 21a vs. 21b, 24a vs. 24b, 28a vs. 28b).

Table 2. In vitro anticancer activity (IC₅₀, μM) of compounds 20a/b–31a/b.

**Table 2.** In vitro anticancer activity (IC₅₀, μM) of compounds **20a/b**–**31a/b**.
Compounds	IC₅₀ (μM)
Compounds	HL-60	SMMC-7721	A-549	MCF-7	SW480
20a	3.02	18.26	18.77	25.00	38.97
20b	>40	>40	>40	>40	>40
21a	0.49	1.26	1.52	6.70	4.03
21b	>40	>40	>40	>40	>40
22a	>40	>40	>40	>40	>40
22b	>40	>40	>40	>40	>40
23a	>40	>40	38.83	36.42	>40
23b	>40	>40	>40	>40	>40
24a	8.57	14.21	17.86	28.31	>40
24b	>40	>40	>40	>40	>40
25a	>40	>40	>40	>40	>40
25b	>40	>40	>40	>40	>40
26a	>40	>40	>40	>40	>40
26b	6.85	15.53	18.20	13.61	14.78
27a	>40	>40	>40	>40	>40
27b	15.27	>40	37.58	28.24	>40
28a	14.94	20.18	35.22	31.80	35.35
28b	>40	>40	>40	>40	>40
29a	>40	>40	>40	>40	>40
29b	>40	>40	>40	>40	>40
30a	15.01	21.69	18.29	21.56	23.11
30b	13.77	16.30	17.75	23.38	39.56
31a	>40	>40	>40	>40	>40
31b	>40	>40	>40	>40	>40
Etoposide (2)	0.31	8.12	11.92	32.82	17.11
Cisplatin	1.17	6.43	9.24	15.86	13.42

3. Experimental Section

3.1. General

Melting points were uncorrected. MS data were obtained in the ESI mode on API Qstar Pulsar instrument (MDS Sciqaszex, Concord, ON, Canada). HRMS data were obtained in the ESI mode on a LCMS-IT-TOF instrument (Shimadzu, Kyoto, Japan). NMR spectra were acquired on Bruker AV-400 or DRX-500 or Bruker AVANCE Ш-600 instruments (Bruker BioSpin GmbH, Rheinstetten, Germany), using tetramethylsilane (TMS) as an internal standard. Column chromatography (CC) was performed on flash silica gel (200–300 mesh; Qingdao Makall Group Co., Ltd; Qingdao; China). All reactions were monitored using thin-layer chromatography (TLC) on silica gel plates.

3.2. General Procedure for the Synthesis of Compounds 12a/b–17a/b

D-sugar (5 mmol) was suspended in propargyl alcohol 4/5 (25 mmol) and stirred at 65 °C. H₂SO₄-silica (25 mg) was added and stirring was continued until all solids had dissolved (~2.5 h). After cooling to room temperature, the reaction mixture was transferred to a short silica gel column (CHCl₃:CH₃OH = 15:1→9:1) to afford the desired propargyl glycosides 6–11. Then, to a solution of a propargyl glycosides 6–11 (1 mmol) in pyridine (4 mL) at 0 °C butyryl anhydride (4 mL) was added. The reaction mixture was stirred overnight until the starting material disappeared as indicated by TLC. The reaction mixture was diluted with water (20 mL) and extracted with ethyl acetate (3 × 20 mL). The organic layer was washed with 10% aqueous hydrochloric acid (20 mL) and brine (20 mL). The organic layer was dried over magnesium sulfate and evaporated to give a residue, which was chromatographed on silica gel with petroleum ether-acetone = 4:1→2:1 to give the perbutyrylated product 12\a/b–17a/b.

3.2.1. 2-Propyn-1-yl-per-O-butyryl-α-d-galactopyranose (12a)

Yield: 56%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.50 (d, 1H, J = 2.7 Hz, C⁴-H), 5.36 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³-H), 5.32 (d, 1H, J = 4.0 Hz, C¹-H), 5.15 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 4.39–4.32 (m, 3H), 4.12 (d, 2H, J = 7.2 Hz, CH₂-C≡CH), 2.92 (t, 1H, J = 2.2 Hz, C≡CH), 2.42 (t, 2H, J = 8.0 Hz, COCH₂), 2.31 (m, 4H, 2 × COCH₂), 2.20 (t, 2H, J = 8.0 Hz, COCH₂), 1.68–1.58 (m, 8H, 4 × CH₂CH₃), 1.00–0.92 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.3 (C=O), 174.2 (C=O), 174.1 (C=O), 173.7 (C=O), 96.1 (C-1), 79.6 (C≡CH), 77.0 (C≡CH), 69.2, 69.0, 68.7, 68.2, 62.5 (C-6), 56.0 (CH₂-C≡C), 36.8 (CH₂C=O), 36.8 (CH₂C=O), 36.8 (CH₂C=O), 36.7 (CH₂C=O), 19.7 (CH₂CH₃), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.3 (CH₂CH₃), 14.2 (CH₂CH₃), 14.2 (CH₂CH₃), 14.2 (CH₂CH₃); ESIMS: m/z 521 [M+Na]⁺, HRESIMS: calcd for C₂₅H₃₈O₁₀Na [M+Na]⁺ 521.2357, found 521.2366.

3.2.2. 2-Propyn-1-yl-per-O-butyryl-β-d-galactopyranose (12b)

Yield: 33%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.42 (d, 1H, J = 2.8 Hz, C⁴-H), 5.19 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³-H), 5.14 (d, 1H, J = 8.0 Hz, C¹-H), 4.86–4.84 (m, 2H), 4.35 (d, 2H, J = 1.9 Hz), 4.14 (s, 2H, CH₂-C≡CH), 2.93 (t, 1H, J = 2.2 Hz, C≡CH), 2.42–2.18 (m, 8H, 4 × COCH₂), 1.71–1.53 (m, 8H, 4 × CH₂CH₃), 0.99–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.5 (C=O), 174.3 (C=O), 173.8 (C=O), 173.7 (C=O), 100.0 (C-1), 79.4 (C≡CH), 76.8 (C≡CH), 72.2, 72.0, 70.0, 68.6, 62.3 (C-6), 56.8 (CH₂-C≡C), 36.9 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 521 [M+Na]⁺, HRESIMS: calcd for C₂₅H₃₈O₁₀Na [M+Na]⁺ 521.2357, found 521.2360.

3.2.3. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-galactopyranoside (13a)

Yield: 57%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.45 (d, 1H, J = 2.4 Hz, C⁴-H), 5.36 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³-H), 5.14–5.10 (m, 2H, C¹-H, C²-H), 4.14 (t, 1H, J = 8.0 Hz), 4.18 (d, 2H, J = 2.4 Hz, CH₂-C≡CH), 4.09 (dd, 1H, J = 6.0 Hz, 10.0 Hz,), 3.84–3.80 (m, 1H), 3.66–3.63 (m, 12H, 3 × OCH₂CH₂O), 2.83 (t, 1H, J = 2.0 Hz, C≡CH), 2.39 (t, 2H, J = 8.0 Hz, COCH₂), 2.30–2.28 (m, 4H, 2 × COCH₂), 2.18 (t, 2H, J = 8.0 Hz, COCH₂), 1.69–1.54 (m, 8H, 4 × CH₂CH₃), 0.98–0.90 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) 174.5 (C=O), 174.3 (C=O), 174.3 (C=O), 173.8 (C=O), 97.7 (C¹-H), 82.7 (C≡CH), 76.0 (C≡CH), 71.6, 71.6, 71.4, 71.2, 70.1, 69.4, 69.2, 68.9, 68.6, 67.6, 62.6 (C-6), 59.0 (CH₂-C≡C), 37.0 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 36.6 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.2 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 653 [M+Na]⁺, HRESIMS: calcd for C₃₁H₅₀O₁₃Na [M+Na]⁺ 653.3144, found 653.3149.

3.2.4. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-galactopyranoside (13b)

Yield: 39%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.40 (d, 1H, J = 2.4 Hz, C⁴-H), 5.13–5.12 (m, 2H, C³-H, C²-H), 4.73 (d, 1H, J = 8.0 Hz, C¹-H), 4.19 (d, 2H, J = 2.0 Hz), 4.12 (s, 2H, CH₂-C≡CH), 3.66–3.60 (m, 12H, 3 × OCH₂CH₂O), 2.85 (t, 1H, J = 2.0 Hz, C≡CH), 2.41 (t, 2H, J = 8.0 Hz, COCH₂), 2.30–2.29 (m, 4H, 2 × COCH₂), 2.17 (t, 2H, J = 8.0 Hz, COCH₂), 1.71–1.53 (m, 8H, 4 × CH₂CH₃), 0.99–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.5 (C=O), 174.4 (C=O), 173.8 (C=O), 173.7 (C=O), 102.2 (C-1), 76.0 (C≡CH), 72.3, 71.8, 71.6, 71.5, 71.4, 70.2, 70.1, 70.0, 68.6, 62.3 (C-6), 59.0 (CH₂-C≡C), 36.9 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 653 [M+Na]⁺, HRESIMS: calcd for C₃₁H₅₀O₁₃Na [M+Na]⁺ 653.3144, found 653.3150.

3.2.5. 2-Propyn-1-yl-per-O-butyryl-α-d-mannopyranoside (14a)

Yield: 60%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.32 (t, 1H, J = 10.0 Hz, C⁴-H), 5.23–5.21 (m, 2H, C³-H, C²-H), 4.98 (s, 1H, C¹-H), 4.30 (t, 2H, J = 2.4 Hz, CH₂-C≡CH), 4.21 (dd, 1H, J = 4.0 Hz, 10.0 Hz), 4.12–4.08 (m, 1H), 4.03–4.00 (m, 1H,), 2.92 (t, 1H, J = 2.4 Hz, C≡CH), 2.37 (t, 2H, J = 8.0 Hz, COCH₂), 2.30–2.24 (m, 4H, 2 × COCH₂), 2.15 (t, 2H, J = 8.0 Hz, COCH₂), 1.69–1.50 (m, 8H, 4 × CH₂CH₃), 0.97–0.86 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.7 (C=O), 173.8 (C=O), 173.8 (C=O), 173.7 (C=O), 97.5 (C-1), 79.3 (C≡CH), 77.0 (C≡CH), 70.6, 70.4, 70.3, 66.6, 62.9 (C-6), 55.7 (CH₂-C≡C), 36.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 521 [M+Na]⁺, HRESIMS: calcd for C₂₅H₃₈O₁₀Na [M+Na]⁺ 521.2357, found 521.2363.

3.2.6. 2-Propyn-1-yl-per-O-butyryl-β-d-mannopyranoside (14b)

Yield: 34%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.44 (d, 1H, J = 3.2 Hz, C²-H), 5.28 (t, 1H, J = 10.0 Hz, C⁴-H), 5.20 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³-H), 5.06 (s, 1H, C¹-H), 4.35 (d, 2H, J = 2.4 Hz, CH₂-C≡CH), 4.26 (dd, 1H, J = 4.0 Hz. 10.0 Hz), 4.19–4.16 (m, 1H), 3.86–3.82 (m, 1H), 2.94 (t, 1H, J = 2.4 Hz, C≡CH), 2.40 (t, 2H, J = 8.0 Hz, COCH₂), 2.34 (t, 2H, J = 8.0 Hz, COCH₂), 2.28 (t, 2H, J = 8.0 Hz, COCH₂), 2.18 (t, 2H, J = 8.0 Hz, COCH₂), 1.72–1.64 (m, 4H, 2 × CH₂CH₃), 1.62–1.53 (m, 4H, 2 × CH₂CH₃), 1.00–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.8 (C=O), 174.4 (C=O), 173.8 (C=O), 173.7 (C=O), 97.3 (C-1), 79.1 (C≡CH), 77.1 (C≡CH), 73.5, 82.5, 70.2, 66.8, 62.9 (C-6), 56.7 (CH₂-C≡C), 36.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 521 [M+Na]⁺, HRESIMS: calcd for C₂₅H₃₈O₁₀Na [M+Na]⁺ 521.2357, found 521.2364.

3.2.7. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-mannopyranoside (15a)

Yield: 62%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.34 (t, 1H, J = 10.0 Hz, C⁴-H), 5.30 (d, 1H, J = 3.2 Hz, C²-H), 5.28–5.27 (m, 2H, C³-H, C¹-H), 4.22–4.20 (m, 1H), 4.19 (d, 2H, J = 2.4 Hz, CH₂-C≡CH), 4.15–4.12 (m, 1H), 3.88–3.84 (m, 1H), 3.71–3.66 (m, 12H, 3 × OCH₂CH₂O), 2.85 (t, 1H, J = 2.4 Hz, C≡CH), 2.41 (t, 2H, J = 8.0 Hz, COCH₂), 2.34 (t, 2H, J = 8.0 Hz, COCH₂), 2.32 (t, 2H, J = 8.0 Hz, COCH₂), 2.19 (t, 2H, J = 8.0 Hz, COCH₂), 1.73–1.65 (m, 4H, 2 × CH₂CH₃), 1.63–1.54 (m, 4H, 2 × CH₂CH₃), 1.01–0.90 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.8 (C=O), 173.9 (C=O), 173.8 (C=O), 173.8 (C=O), 99.0 (C-1), 80.7 (C≡CH), 76.0 (C≡CH), 71.7, 71.6, 71.4, 71.2, 70.8, 70.5, 70.1, 69.9, 68.4, 66.8, 63.1 (C-6), 59.0 (CH₂-C≡C), 36.9 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 653 [M+Na]⁺, HRESIMS: calcd for C₃₁H₅₀O₁₃Na [M+Na]⁺ 653.3144, found 653.3149.

3.2.8. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-mannopyranoside (15b)

Yield: 34%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.24–5.22 (m, 1H, C⁴-H), 5.13 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³-H), 4.86–4.84 (m, 1H, C²-H), 4.81 (d, 1H, J = 2.0 Hz, C¹-H), 4.43 (dd, 1H, J = 2.0 Hz, 10.0 Hz), 4.29–4.25 (m, 1H), 4.19 (d, 2H, J = 2.4 Hz, CH₂-C≡CH), 3.95–3.90 (m, 1H), 3.85–3.82 (m, 1H), 3.69–3.66 (m, 12H, 3 × OCH₂CH₂O), 2.85 (t, 1H, J = 2.4 Hz, C≡CH), 2.35–2.29 (m, 8H, 4 × COCH₂), 1.70–1.60 (m, 8H, 4 × CH₂CH₃), 0.99–0.94 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.1 (C=O), 174.4 (C=O), 174.4 (C=O), 174.0 (C=O), 99.0 (C-1), 80.7 (C≡CH), 76.0 (C≡CH), 73.0, 72.1, 71.7, 71.6, 71.4, 71.3, 70.8, 70.1, 68.2, 66.0, 64.2 (C-6), 59.0 (CH₂-C≡C), 37.0 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 653 [M+Na]⁺, HRESIMS: calcd for C₃₁H₅₀O₁₃Na [M+Na]⁺ 653.3144, found 653.3144.

3.2.9. 2-Propyn-1-yl-per-O-butyryl-α-d-xylopyranoside (16a)

Yield: 61%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.46 (t, 1H, J = 10.0 Hz, C³-H), 5.23 (d, 1H, J = 4.0 Hz, C¹-H), 5.04–4.97 (m, 1H, C²-H), 4.89–4.85 (m, 1H, C⁴-H), 4.36–4.24 (m, 2H, CH₂-C≡CH), 3.80 (dd, 1H, J = 6.0 Hz, 10.0 Hz), 3.63 (t, 1H, J = 10.0 Hz), 2.91 (t, 1H, J = 2.4 Hz, C≡CH), 2.30–2.25 (m, 6H, 3 × COCH₂), 1.64–1.57 (m, 6H, 3 × CH₂CH₃) 0.94–0.92 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.0 (C=O), 174.0 (C=O), 173.8 (C=O), 95.6 (C-1), 79.5 (C≡CH), 76.7 (C≡CH), 71.9, 70.5, 70.3, 59.8 (C-6), 55.8 (CH₂-C≡C), 36.9 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 421 [M+Na]⁺, HRESIMS: calcd for C₂₀H₃₀O₈Na [M+Na]⁺ 421.1833, found 421.1838.

3.2.10. 2-Propyn-1-yl-per-O-butyryl-β-d-xylopyranoside (16b)

Yield: 29%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.26 (t, 1H, J = 9.0 Hz, C³-H), 4.96–4.88 (m, 2H, C⁴-H, C²-H), 4.79 (d, 1H, J = 8.0 Hz, C¹-H), 4.33 (t, 2H, J = 1.6 Hz, CH₂-C≡CH), 4.08 (dd, 1H, J = 5.0 Hz, 12.0 Hz), 3.47 (dd, 1H, J = 10.0 Hz, 12.0 Hz), 2.93 (t, 1H, J = 2.4 Hz, C≡CH), 2.29–2.23 (m, 6H, 3 × COCH₂), 1.65–1.55 (m, 6H, 3 × CH₂CH₃), 0.94–0.91 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 173.9 (C=O), 193.9 (C=O), 173.6 (C=O), 100.1 (C-1), 79.4 (C≡CH), 76.7 (C≡CH), 73.0, 72.0, 70.2, 63.3 (C-5), 56.7 (CH₂-C≡C), 36.9 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 421 [M+Na]⁺, HRESIMS: calcd for C₂₀H₃₀O₈Na [M+Na]⁺ 421.1833, found 421.1836.

3.2.11. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-xylopyranoside (17a)

Yield: 62%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.48 (t, 1H, J = 10.0 Hz, C³-H), 5.08 (d, 1H, J = 4.0 Hz, C¹-H), 5.00–4.94 (m, 1H, C⁴-H), 4.83 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 4.19 (d, 2H, J = 2.4 Hz, CH₂-C≡CH), 3.85–3.80 (m, 1H), 3.75–3.73 (m, 1H), 3.71–3.65 (m, 12H, 3 × OCH₂CH₂O), 2.86 (t, 1H, J = 2.0 Hz, C≡CH), 2.32–2.24 (m, 6H, 3 × COCH₂), 1.64–1.56 (m, 6H, 3 × CH₂CH₃), 0.95–0.90 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.1 (C=O), 174.0 (C=O), 173.9 (C=O), 97.3 (C-1), 80.7 (C≡CH), 76.0 (C≡CH), 72.2, 71.7, 71.6, 71.5, 71.3, 70.7, 70.5, 70.1, 68.6, 59.4 (C-5), 59.1 (CH₂-C≡C), 36.9 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 553 [M+Na]⁺, HRESIMS: calcd for C₂₆H₄₂O₁₁Na [M+Na]⁺ 553.2619, found 553.2625.

3.2.12. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-xylopyranoside (17b)

Yield: 28%. ¹H-NMR (CDCl₃, 400 MHz) δ 5.23 (t, 1H, J = 9.0 Hz, C³-H), 4.96–4.86 (m, 2H, C²-H, C⁴-H), 4.65 (d, 1H, J = 8.0 Hz, C¹-H), 4.19 (d, 2H, J = 2.4 Hz, CH₂C≡CH), 4.06 (dd, 1H, J = 6.0 Hz, 12.0 Hz), 3.91–3.86 (m, 1H), 3.66–3.61 (m, 12H, 3 × OCH₂CH₂O), 2.86 (t, 1H, J = 2.4 Hz, C≡CH), 2.31–2.22 (m, 6H, 3 × COCH₂), 1.63–1.54 (m, 6H, 3 × CH₂CH₃), 0.93–0.90 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 173.9 (C=O), 173.9 (C=O), 173.6 (C=O), 102.3 (C-1), 80.7 (C≡CH), 76.0 (C≡CH), 73.1, 72.4, 71.6, 71.6, 71.4, 71.4, 70.3, 70.1, 69.9, 63.4 (C-5), 59.1 (CH₂-C≡C), 36.9 (COCH₂), 36.9 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 553 [M+Na]⁺, HRESIMS: calcd for C₂₆H₄₂O₁₁Na [M+Na]⁺ 553.2619, found 553.2627.

3.3. Click Chemistry-General Procedure

To a solution of a terminal-alkyne 12a/b–17a/b (0.1 mmol) and 4β-azidopodophyllotoxin analogues 18 or 19 (0.1 mmol) in t−BuOH-H₂O (1:2, 1.0 mL) at room temperature were added copper (II) sulfate pentahydrate (0.01 mmol) and sodium ascorbate (1.0 M in H₂O, 3 drops). The reaction mixture was stirred at room temperature for 2 h until the starting material disappeared as indicated by TLC. Then, the mixture was diluted with water (10 mL) and extracted with ethyl acetate (3 × 10 mL), and the combined organic layer was dried over sodium sulfate. The solvent was evaporated and the residue was purified by column chromatography to afford the cycloaddition product 20a/b–31a/b (82%–92%).

3.3.1. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20a)

White amorphous powder, yield 90% (after chromatography with petroleum ether/acetone, 1:1); mp 87 °C;

{[α]}_{D}^{25.7}

: +28.7 (c 0.27, CH₃OH); ¹H-NMR (CD₃OD, 500 MHz) δ 7.87 (s, 1H, C^5''-H), 6.71 (s, 1H, C⁵-H), 6.61 (s, 1H, C⁸-H), 6.43 (s, 2H, C^2', C^6'-H), 6.26 (d, 1H, J = 5.0 Hz, C⁴-H), 5.98 (d, 2H, J = 10.0 Hz, OCH₂O), 5.50 (d, 1H, J = 4.0 Hz, C^4'''-H), 5.36 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C^3'''-H), 5.26 (d, 1H, J = 4.0 Hz, C^1'''-H), 5.00 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C^2'''-H), 4.74–4.72 (m, 2H), 4.31 (d, 1H, J = 5.5 Hz, C¹-H), 4.10–4.05 (m, 1H), 4.01–3.99 (m, 1H), 3.74 (s, 2H), 3.75 (s, 6H, C^3', C^5'-OCH₃), 3.72 (s, 3H, C^4'-OCH₃), 3.39 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 3.15–3.11 (m, 1H, C³-H), 2.34 (t, 2H, J = 9.0 Hz, COCH₂), 2.23 (t, 2H, J = 9.0 Hz, COCH₂), 2.16–2.14 (m, 4H, 2 × COCH₂), 1.69–1.58 (m, 2H, CH₂CH₃), 1.55–1.48 (m, 6H, 3 × CH₂CH₃), 0.92–0.82 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 125 MHz) δ 174.2 (C-12), 173.0 (C=O), 172.7 (C=O), 172.6 (C=O), 172.3 (C=O), 152.4 (C-3^', C-5^'), 149.0 (C-7), 147.7 (C-6), 143.1 (C-4^''), 136.7 (C-1^'), 135.2 (C-9), 133.2 (C-10), 125.4 (C-4^'), 124.8 (C-5^''), 109.7 (C-5), 108.3 (C-8), 107.8 (C-2^', C-6^'), 101.8 (OCH₂O), 95.0 (C-1^'''), 67.7, 67.6, 67.3 (C-11), 67.2, 66.3, 60.9 (C-6^''), 59.9 (C-6^'''), 59.5 (4^'-OCH₃), 58.3 (C-2), 55.1 (3^', 5^'-OCH₃), 43.4 (C-4), 41.0 (C-1), 37.0 (C-3), 35.2 (COCH₂), 35.2 (COCH₂), 35.1 (COCH₂), 35.1 (COCH₂), 18.0 (CH₂CH₃), 17.9 (CH₂CH₃), 17.8 (CH₂CH₃), 17.6 (CH₂CH₃), 12.5 (CH₂CH₃), 12.5 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃); ESIMS: m/z 960 [M+Na]⁺, HRESIMS: calcd for C₄₇H₅₉N₃O₁₇H [M+H]⁺ 938.3917, found 938.3915.

3.3.2. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20b)

White amorphous powder, yield 90% (after chromatography with petroleum ether/acetone, 1:1); mp 92 °C;

{[α]}_{D}^{25.8}

: −33.2 (c 0.16, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.72 (s,1H, C^5''-H), 6.67 (s, 1H, C⁵-H), 6.58 (s, 1H, C⁸-H), 6.41 (s, 2H, C^2', C^6'-H), 6.24 (d, 1H, J = 4.3 Hz, C⁴-H), 5.94 (d, 2H, J = 7.4 Hz, OCH₂O), 5.42 (d, 1H, J = 2.6 Hz, C^4'''-H), 5.18–5.09 (m, 2H, C^3'''-H, C^2'''-H), 4.79 (d, 1H, J = 8.0 Hz, C^1'''-H), 4.78–4.77 (m, 2H), 3.34–3.32 (m, 1H), 4.18–4.11 (m, 2H), 3.79 (s, 2H), 3.72 (s, 6H, C^3', C^5'-OCH₃), 3.70 (s, 3H, C^4'-OCH₃), 3.39 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 3.15–3.11 (m, 1H, C³-H), 2.38 (t, 2H, J = 8.0 Hz, COCH₂), 2.27 (t, 2H, J = 8.0 Hz, COCH₂), 2.17–2.15 (m, 4H, 2 × COCH₂), 1.67–1.47 (m, 8H, 4 × CH₂CH₃); 0.96–0.82 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.6 (C-12), 174.4 (C=O), 174.3 (C=O), 173.7 (C=O), 173.7 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 145.5 (C-4^''), 138.6 (C-1^'), 136.7 (C-9), 134.8 (C-10), 126.9 (C-4^'), 126.0 (C-5^''), 111.3 (C-5), 109.9 (C-8), 109.5 (C-2^', C-6^'), 103.3 (OCH₂O), 101.5 (C-1^'''), 72.1, 72.0, 70.1, 68.9 (C-11), 68.6, 63.3 (C-6^''), 62.3 (C-6^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 56.7 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.8 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 960 [M+Na]⁺, HRESIMS: calcd for C₄₇H₅₉N₃O₁₇Na [M+Na]⁺ 938.3917, found 938.3898.

3.3.3. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (21a)

White amorphous powder, yield 89% (after chromatography with petroleum ether/acetone, 1:1); mp 89 °C;

{[α]}_{D}^{25.8}

: +22.2 (c 0.22, CH₃OH); ¹H-NMR (CD₃OD, 500 MHz) δ 8.24 (s, 1H, C^5''-H), 6.61 (s, 3H, C⁵-H, C²^', C⁶^'-H), 6.24 (s, 1H, C⁸-H), 5.99–5.91 (m, 3H, C⁴-H, OCH₂O), 5.52 (d, 1H, J = 4.0 Hz, C^4'''-H), 5.42 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³^'''-H), 5.32 (d. 1H, J = 4.0 Hz. C¹^'''-H), 5.12 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C^2'''-H), 4.80–4.77 (m, 2H), 4.67 (d, 1H, J = 5.0 Hz, C¹-H), 4.43 (t, 1H, J = 8.0 Hz, C^5'''-H), 4.25 (t, 1H, J = 8.0 Hz), 4.21–4.17 (m, 1H), 4.16–4.06 (m, 2H), 3.79 (s, 6H, C^3', C^5'-OCH₃), 3.57–3.49 (m, 1H, C³-H), 3.19 (dd, 1H, J = 5.0 Hz, 10.0 Hz, C²-H), 2.42 (t, 2H, J = 8.0 Hz, COCH₂), 2.29–2.20 (m, 6H, 3 × COCH₂), 1.73–1.66 (m, 2H, CH₂CH₃), 1.61–1.52 (m, 6H, 3 × CH₂CH₃), 1.00–0.86 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 125 MHz) δ 175.9 (C-12), 174.6 (C=O), 174.3 (C=O), 174.2 (C=O), 173.9 (C=O), 149.7 (C-7), 149.1 (C-6), 148.7 (C-3^', C-5^'), 144.9 (C-4^''), 135.8 (C-1^'), 134.3 (C-9), 131.7 (C-10), 129.0 (C-4^'), 125.8 (C-5^''), 110.0 (C-5), 109.5 (C-2^', C-6^'), 107.3 (C-8), 103.1 (OCH₂O), 96.9 (C-1^'''), 71.3 (C-11), 69.3, 69.3, 68.9, 68.0, 64.0 (C-4), 62.5 (C-6^'''), 61.8 (C-6^''), 57.0 (3^', 5^'-OCH₃), 46.6 (C-1), 45.1 (C-2), 40.0 (C-3), 36.8 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.5 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.5 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 946 [M+Na]⁺, HRESIMS: calcd for C₄₆H₅₇N₃O₁₇Na [M+Na]⁺ 946.3580, found 946.3555.

3.3.4. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (21b)

White amorphous powder, yield 91% (after chromatography with petroleum ether/acetone, 1:1); mp 103–105 °C;

{[α]}_{D}^{25.6}

: −45.1 (c 0.27, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.72 (s, 1H, C⁵^''-H), 6.66 (s, 1H, C⁵-H), 6.61 (s, 1H, C⁸-H), 6.38 (s, 2H, C²^', C⁶^'-H), 6.23 (d, 1H, J = 3.9 Hz, C⁴-H), 5.95 (d, 2H, J = 8.2 Hz, OCH₂O), 5.42 (d, 1H, J = 2.4 Hz, C⁴^'''-H), 5.14–5.11 (m, 2H, C³^'''-H, C²^'''-H), 4.81 (d, 1H, J = 8.0 Hz, C¹^'''-H), 4.79–4.75 (m, 3H), 4.36 (m, 1H), 4.17–4.09 (m, 4H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.35–3.34 (m, 1H, C²-H), 3.15–3.11 (m, 1H, C³-H), 2.38 (t, 2H, J = 7.2 Hz, COCH₂), 2.27 (t, 2H, J = 7.2 Hz, COCH₂), 2.17 (t, 2H, J = 7.2 Hz, COCH₂), 2.15 (t, 2H, J = 7.2 Hz, COCH₂), 1.68–1.48 (m, 8H, 4 × CH₂CH₃), 0.97–0.83 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.8 (C-12), 174.5 (C=O), 174.3 (C=O), 173.8 (C=O), 173.8 (C=O), 150.5 (C-7), 149.2 (C-6), 148.7 (C-3^', C-5^'), 145.4 (C-4^''), 136.1 (C-1^'), 135.1 (C-9), 131.3 (C-10), 126.9 (C-4^'), 126.0 (C-5^''), 111.3 (C-5), 109.8 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 101.5 (C-1^'''), 72.1, 72.0, 70.1, 62.2, 68.5 (C-11), 63.2 (C-6^''), 62.2 (C-6^'''), 59.9 (C-2), 56.8 (3^', 5^'-OCH₃), 44.8 (C-4), 42.7 (C-1), 38.5 (C-3), 36.8 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 36.6 (COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 946 [M+Na]⁺, HRESIMS: calcd for C₄₆H₅₇N₃O₁₇H [M+H]⁺ 924.3761, found 924.3745.

3.3.5. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22a)

White amorphous powder, yield 82% (after chromatography with petroleum ether/acetone, 1:1); mp 82 °C;

{[α]}_{D}^{25.7}

: −26.2 (c 0.18, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.81 (s, 1H, C⁵^''-H), 6.70 (s, 1H, C⁵-H), 6.63 (s, 1H, C⁸-H), 6.42 (s, 2H, C²^', C⁶^'-H), 6.27 (d, 1H, J = 4.8 Hz, C⁴-H), 5.98 (d, 2H, J = 8.4 Hz, OCH₂O), 5.41 (d, 1H, J = 1.2 Hz, C⁴^'''-H), 5.16–5.10 (m, 3H, C¹^'''-H, C³^'''-H, C²^'''-H), 4.81 (d, 1H, J = 5.2 Hz, C¹-H), 4.74–4.72 (m, 1H), 4.65–4.63 (m, 2H), 4.41–4.36 (m, 1H), 4.13–4.12 (m, 2H), 3.92–3.86 (m, 1H), 3.81–3.80 (m, 1H), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.72 (s, 3H, C⁴^'-OCH₃), 3.66–3.58 (m, 12H, 3 × OCH₂CH₂O), 3.43 (dd, 1H, J = 1.2 Hz, 10.0 Hz, C²-H), 3.19–3.14 (m, 1H, C³-H), 3.36 (t, 2H, J = 8.0 Hz, COCH₂), 2.28–2.26 (m, 4H, 2 × COCH₂), 1.64–1.52 (m, 8H, 4 × CH₂CH₃), 0.96–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.8 (C-12), 174.5 (C=O), 174.3 (C=O), 173.8 (C=O), 173.8 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 146.1 (C-4^''), 138.3 (C-1^'), 136.8 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.9 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 102.3 (C-1^'''), 72.3, 71.8, 71.6, 71.5, 71.4, 70.9, 70.2, 70.1, 68.9 (C-11), 68.6, 65.0 (C-6^''), 63.3 (C-6^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.9 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 1092 [M+Na]⁺, HRESIMS: calcd for C₅₃H₇₁N₃O₂₀Na [M+Na]⁺ 1092.4523, found 1092.4484.

3.3.6. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22b)

White amorphous powder, yield 88% (after chromatography with petroleum ether/acetone, 1:1); mp 75 °C;

{[α]}_{D}^{25.6}

: −25.5 (c 0.14, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.81 (s,1H, C⁵^''- H), 6.70 (s, 1H, C⁵-H), 6.62 (s, 1H, C⁸-H), 6.42 (s, 2H, C²^', C⁶^'-H), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.96 (d, 2H, J = 9.2 Hz, OCH₂O), 5.41 (d, 1H, J = 2.8 Hz, C⁴^'''-H), 5.16–5.12 (m, 2H, C³^'''-H, C²^'''-H), 4.80 (d, 1H, J = 5.2 Hz, C¹-H), 4.74 (d, 1H, J = 7.2 Hz, C¹^'''-H), 4.62 (s, 2H), 4.40–4.34 (m, 1H), 4.13-4.12 (m, 2H), 3.91–3.86 (m, 1H), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.72 (s, 3H, C⁴^'-OCH₃), 3.66–3.57 (m, 12H, 3 × OCH₂CH₂O), 3.44 (dd, 1H, J = 5.2 Hz, 10.8 Hz, C²-H), 3.18–3.13 (m, 1H, C³-H), 3.35 (t, 2H, J = 8.0 Hz, COCH₂), 2.29–2.27 (m, 4H, 2 × COCH₂), 2.18 (t, 2H, J = 7.6 Hz, COCH₂), 1.67–1.52 (m, 8H, 4 × CH₂CH₃), 0.95–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.5 (C=O), 174.3 (C=O), 173.8 (C=O), 173.8 (C=O), 154.0 (C-3^', C-5^'), 150.5 (C-7), 149.3 (C-6), 146.1 (C-4^''), 138.3 (C-1^'), 136.8 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.9 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.5 (C-2^', C-6^'), 103.3 (OCH₂O), 102.3 (C-1^'''), 72.3, 71.8, 71.6, 71.5, 71.4, 70.9, 70.2, 70.1, 68.9 (C-11), 68.7, 65.0 (C-6^''), 62.4 (C-6^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 56.7 (3^', 5^'-OCH₃), 44.8 (C-4), 42.5 (C-1), 38.6 (C-3), 36.9 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.3 (CH₂CH₃), 19.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 1078 [M+Na]⁺, HRESIMS: calcd for C₅₂H₆₉N₃O₂₀Na [M+Na]⁺ 1078.4367, found 1078.4345.

3.3.7. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (23a)

White amorphous powder, yield 87% (after chromatography with petroleum ether/acetone, 1:1); mp 84–85 °C;

{[α]}_{D}^{25.9}

: +6.7 (c 0.23, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.79 (s,1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.65 (s, 1H, C⁸-H), 6.38 (s, 2H, C²^', C⁶^'-H), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.98 (d, 2H, J = 5.6 Hz, OCH₂O), 5.47 (d, 1H, J = 2.4 Hz, C⁴^'''-H), 5.37 (dd, 1H, J = 3.2 Hz, 10.8 Hz, C²^'''-H), 5.15–5.08 (m, 2H, C¹^'''-H, C³^'''-H), 4.77 (d, 1H, J = 4.4 Hz, C¹-H), 4.63 (s, 2H), 4.44–4.37 (m, 2H), 4.12–4.06 (m, 1H), 3.84–3.80 (m, 1H), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.67–3.60 (m, 12H, 3 × OCH₂CH₂CO), 3.40 (dd, 1H, J = 4.4 Hz, 10.8 Hz, C²-H), 3.19–3.13 (m, 1H, C³-H), 2.39 (t, 2H, J = 8.0 Hz, COCH₂), 2.29–2.27 (m, 4H, 2 × COCH₂), 2.19 (t, 2H, J = 8.0 Hz, COCH₂), 1.69–1.53 (m, 8H, 2 × CH₂CH₃), 0.98–0.90 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.4 (C-12), 173.0 (C=O), 172.8 (C=O), 172.8 (C=O), 172.4 (C=O), 149.0 (C-7), 147.7 (C-6), 147.2 (C-3^', C-5^'), 144.6 (C-4^''), 134.5 (C-1^'), 133.6 (C-9), 129.8 (C-10), 125.3 (C-4^'), 124.2 (C-5^''), 109.7 (C-5), 108.2 (C-8), 107.8 (C-2^', C-6^'), 101.7 (OCH₂O), 96.1 (C-1^'''), 70.0, 69.6, 69.6, 69.4, 67.8, 67.7, 67.3 (C-11), 67.0, 63.5 (C-6^''), 60.0 (C-6^'''), 58.3 (C-2), 55.2 (3^', 5^'-OCH₃), 43.2 (C-4), 41.1 (C-1), 37.0 (C-3), 35.2 (COCH₂), 35.1 (COCH₂), 35.1 (COCH₂), 35.1 (COCH₂), 18.0 (CH₂CH₃), 17.9 (CH₂CH₃), 17.7 (CH₂CH₃), 17.6 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃); ESIMS: m/z 1078 [M+Na]⁺, HRESIMS: calcd for C₅₂H₆₉N₃O₂₀Na [M+Na]⁺ 1078.4367, found 1078.4345.

3.3.8. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (23b)

White amorphous powder, yield 85% (after chromatography with petroleum ether/acetone, 1:1); mp 77°C;

{[α]}_{D}^{25.6}

: −21.5 (c 0.29, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.81 (s, 1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.63 (s, 1H, C⁸-H), 6.39 (s, 2H, C²^', C⁶^'-H), 6.25 (d, 1H, J = 4.8 Hz, C⁴-H), 5.96 (d, 2H, J = 8.8 Hz, OCH₂O), 5.41 (d, 1H, J = 2.8 Hz, C⁴^'''-H), 5.16–5.10 (m, 2H, C³^'''-H, C²^'''-H), 4.77 (d, 1H, J = 4.8 Hz, C¹-H), 4.73 (d, 1H, J = 7.2 Hz, C¹^'''-H), 4.62 (s, 2H), 4.39–4.36 (m, 1H), 4.13 (s, 2H), 3.91–3.86 (m, 1H), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.66–3.57 (m, 12H, 3 × OCH₂CH₂CO), 3.40 (dd, 1H, J = 4.8Hz, 10.8 Hz, C²-H), 3.17–3.13 (m, 1H, C³-H), 2.36 (t, 2H, J = 7.6 Hz, COCH₂), 2.29–2.27 (m, 4H, 2 × COCH₂), 2.18 (t, 2H, J = 7.6 Hz, COCH₂), 1.67–1.52 (m, 8H, 4 × CH₂CH₃) 0.95–0.89 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.8 (C-12), 173.4 (C=O), 174.2 (C=O), 172.7 (C=O), 172.7 (C=O), 149.4 (C-7), 148.1 (C-6), 147.6 (C-3^', C-5^'), 145.0 (C-4^''), 134.9 (C-1^'), 134.0 (C-9), 130.2 (C-10), 125.8 (C-4^'), 124.8 (C-5^''), 110.2 (C-5), 108.7 (C-8), 108.3 (C-2^', C-6^'), 102.1 (OCH₂O), 101.1 (C-1^'''), 72.3, 71.8, 71.6, 71.5, 71.4, 70.9, 70.2, 70.1, 68.9 (C-11), 68.6, 65.0 (C-6^''), 62.4 (C-6^'''), 59.9 (C-2), 55.7 (3^', 5^'-OCH₃), 43.6 (C-4), 41.5 (C-1), 37.4 (C-3), 35.8 (COCH₂), 35.6 (COCH₂), 35.6 (COCH₂), 35.5 (COCH₂), 18.4 (CH₂CH₃), 18.4 (CH₂CH₃), 18.2 (CH₂CH₃), 18.0 (CH₂CH₃), 12.9 (CH₂CH₃), 12.8 (CH₂CH₃), 12.8 (CH₂CH₃), 12.8 (CH₂CH₃); ESIMS: m/z 1078 [M+Na]⁺, HRESIMS: calcd for C₅₂H₆₉N₃O₂₀H [M+H]⁺ 1056.4547, found 1056.4528.

3.3.9. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24a)

White amorphous powder, yield 90% (after chromatography with petroleum ether/acetone, 1:1); mp 80 °C;

{[α]}_{D}^{26.8}

: −3.8 (c 0.27, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.85 (s, 1H, C⁵^''-H), 6.68 (s, 1H, C⁵-H), 6.57 (s, 1H, C⁸-H), 6.40 (s, 2H, C²^', C⁶^'-H), 6.24 (d, 1H, J = 4.4 Hz, C⁴-H), 5.93 (d, 2H, J = 9.2 Hz, OCH₂O), 5.35 (t, 1H, J = 10.0 Hz, C⁴^'''-H), 5.25 (dd, 1H, J = 2.8 Hz, 10.0 Hz, C³^'''-H), 5.19–5.18 (m, 1H, C²^'''-H), 4.93 (d, 1H, J = 2.8 Hz, C¹^'''-H), 4.78–4.76 (m, 2H), 4.68 (s, 1H, C¹-H), 4.35 (t, 1H, J = 6.8 Hz), 4.22–4.20 (m, 1H), 4.10–4.06 (m, 2H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.71 (s, 3H, C⁴^'-OCH₃), 3.30 (dd, 1H, J = 4.8 Hz, 10.4 Hz, C²-H), 3.20–3.15 (m, 1H, C³-H), 3.38–3.34 (m, 8H, 4 × COCH₂), 1.69–1.62 (m, 4H, 2 × CH₂CH₃), 1.60–1.51 (m, 4H, 2 × CH₂CH₃), 0.97–0.87 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.7 (C=O), 174.0 (C=O), 173.9 (C=O), 173.7 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 144.9 (C-4^''), 138.3 (C-1^'), 136.8 (C-9), 134.8 (C-10), 126.9 (C-4^'), 126.2 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.5 (C-2^', C-6^'), 103.3 (OCH₂O), 98.2 (C-1^'''), 70.6, 70.6, 70.2, 68.9 (C-11), 66.6, 62.9 (C-6^''), 61.7 (C-6^'''), 61.0 (4^'-OCH₃), 59.9 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.50 (C-1), 38.6 (C-3), 36.8 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 36.7(COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 960 [M+Na]⁺, HRESIMS: calcd for C₄₇H₅₉N₃O₁₇H [M+H]⁺ 938.3917, found 938.3906.

3.3.10. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24b)

White amorphous powder, yield 86% (after chromatography with petroleum ether/acetone, 1:1); mp 92–93 °C;

{[α]}_{D}^{26.8}

: −52.1 (c 0.17, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.74 (s, 1H, C⁵^''-H), 6.66 (s, 1H, C⁵-H), 6.59 (s, 1H, C⁸-H), 6.40 (s, 2H, C²^', C⁶^'-H), 6.22 (d, 1H, J = 4.4 Hz, C⁴-H), 5.94 (d, 2H, J = 10.0 Hz, OCH₂O), 5.42 (d, 1H, J = 2.8 Hz, C²^'''-H), 5.26 (t, 1H, J = 10.0 Hz, C⁴^'''-H), 5.16 (dd, 1H, J = 2.8 Hz, 10.0 Hz, C³^'''-H), 4.99 (s, 1H, C¹^'''-H), 4.84 (s, 1H, C¹-H), 4.77–4.72 (m, 2H), 4.36–4.32 (m, 1H), 4.25 (dd, 1H, J = 4.4 Hz, 10.4 Hz), 4.17–4.12 (m, 1H,), 3.85–3.82 (m, 1H), 3.72 (s, 6H, C³^', C⁵^'-OCH₃), 3.71 (s, 3H, C⁴^'-OCH₃), 3.39 (dd, 1H, J = 4.8 Hz, 10.0 Hz, C²-H), 3.17–3.13 (m, 1H, C³-H), 2.34–2.25 (m, 8H, 4 × COCH₂), 1.66–1.51 (m, 8H, 4 × CH₂CH₃) 0.94–0.88 (t, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.7 (C=O), 174.3 (C=O), 173.8 (C=O), 173.7 (C=O), 154.0 (C-3^', C-5^'), 150.5 (C-7), 149.3 (C-6), 145.3 (C-4^''), 138.3 (C-1^'), 136.7 (C-9), 134.8 (C-10), 126.9 (C-5^''), 126.2 (C-4^'), 111.2 (C-5), 109.4 (C-8), 109.9 (C-2^', C-6^'), 103.3 (OCH₂O), 99.3 (C-1^'''), 73.5, 72.5, 70.3, 69.3 (C-11), 66.8, 63.5 (C-6^''), 62.9 (C-6^'''), 61.1 (4^'-OCH₃), 59.9 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 19.7 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 960 [M+Na]⁺, HRESIMS: calcd for C₄₇H₅₉N₃O₁₇H [M+H]⁺ 938.3917, found 938.3902.

3.3.11. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (25a)

White amorphous powder, yield 92% (after chromatography with CHCl₃/CH₃OH, 9:1); mp 94–96 °C;

{[α]}_{D}^{26.7}

: −46.3 (c 0.17, Pyridine); ¹H-NMR (C₅D₅N, 400 MHz) δ 8.32 (s,1H, C⁵^''-H), 6.82 (s, 1H, C⁵-H), 6.83 (s, 1H, C⁸-H), 6.78 (s, 2H, C²^', C⁶^'-H), 6.55 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 4.4 Hz, OCH₂O), 5.83 (t, 1H, J = 10.0 Hz, C⁴^'''-H), 5.72 (dd, 1H, J = 3.2 Hz, 10.0 Hz, C³^'''-H), 5.68–5.67 (m, 1H, C²^'''-H), 5.38 (s, 1H, C¹^'''-H), 5.18–5.15 (m, 2H), 5.02 (s, 1H, C¹-H), 4.97 (t, 1H, J = 5.2 Hz), 4.55 (dd, 1H, J = 4.8 Hz, 10.0 Hz), 4.48–4.45 (m, 2H), 3.77 (dd, 1H, J = 5.2 Hz, 10.8 Hz, C²-H), 3.72 (s, 6H, C³^', C⁵^'-OCH₃), 3.50–3.45 (m, 1H, C³-H), 2.42–2.38 (m, 4H, 2 × COCH₂), 2.31–2.26 (m, 6H, 3 × COCH₂), 1.70–1.56 (m, 8H, 4 × CH₂CH₃), 0.87–0.80 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (C₅D₅N, 100 MHz) δ 174.1 (C-12), 173.2 (C=O), 172.7 (C=O), 172.5 (C=O), 172.5 (C=O), 149.5 (C-7), 148.7 (C-3^', C-5^'), 148.2 (C-6), 144.2 (C-4^''), 137.3 (C-1^'), 134.6 (C-9), 130.1 (C-10), 126.3 (C-5^''), 125.2 (C-4^'), 110.8 (C-5), 109.7 (C-2^', C-6^'), 109.3 (C-8), 102.4 (OCH₂O), 97.4 (C-1^'''), 69.9, 69.8, 69.6, 67.9 (C-11), 66.1, 62.3 (C-6^''), 61.4 (C-6^'''), 59.0 (C-2), 56.5 (3^', 5^'-OCH₃), 44.1 (C-4), 42.0 (C-1), 38.0 (C-3), 36.2 (COCH₂), 36.0 (COCH₂), 36.0 (COCH₂), 36.0 (COCH₂), 18.7 (CH₂CH₃), 18.7 (CH₂CH₃), 18.7 (CH₂CH₃), 18.5 (CH₂CH₃), 13.8 (CH₂CH₃), 13.7 (CH₂CH₃), 13.7 (CH₂CH₃), 13.6 (CH₂CH₃); ESIMS: m/z 946 [M+Na]⁺, HRESIMS: calcd for C₄₆H₅₇N₃O₁₇H [M+H]⁺ 924.3761, found 924.3752.

3.3.12. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (25b)

White amorphous powder, yield 87% (after chromatography with petroleum ether/acetone, 1:1); mp 99–100 °C;

{[α]}_{D}^{26.8}

: −63.6 (c 0.13, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.73 (s, 1H, C⁵^''-H), 6.66 (s, 1H, C⁵-H), 6.61 (s, 1H, C⁸-H), 6.38 (s, 2H, C²^', C⁶^'-H), 6.22 (d, 1H, J = 4.4 Hz, C⁴-H), 5.95 (d, 2H, J = 9.2 Hz, OCH₂O), 5.42 (d, 1H, J = 2.8 Hz, C²^'''-H), 5.26 (t, 1H, J = 10.0 Hz, C⁴^'''-H), 5.15 (dd, 1H, J = 2.8 Hz, 10.0 Hz, C³^'''-H), 4.99 (s, 1H, C¹^'''-H), 4.86 (d, 1H, J = 4.4 Hz, C¹-H), 4.76–4.73 (m, 2H), 4.37–4.34 (m, 1H), 4.26 (dd, 1H, J = 4.0 Hz, 10.0 Hz), 4.14 (dd, 1H, J = 2.0 Hz, 10.0 Hz), 3.86–3.81 (m, 1H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.34–3.33 (m, 1H, C²-H), 3.18–3.13 (m, 1H, C³-H), 2.35–2.26 (m, 8H, 4 × COCH₂), 1.67–1.52 (m, 8H, 4 × CH₂CH₃), 0.96–0.88 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.9 (C-12), 174.7 (C=O), 174.4 (C=O), 173.4 (C=O), 173.7 (C=O), 150.5 (C-7), 149.2 (C-6), 148.7 (C-3^', C-5^'), 145.3 (C-4^''), 136.0 (C-1^'), 135.1 (C-9), 131.3 (C-10), 126.8 (C-4^'), 126.2 (C-5^''), 111.3 (C-5), 109.8 (C-8), 109.3 (C-2^', C-6^'), 103.3 (OCH₂O), 99.3 (C-1^'''), 73.5, 72.4, 70.3, 66.8, 68.9 (C-11), 63.5 (C-6^''), 62.9 (C-6^'''), 60.0 (C-2), 56.8 (3^', 5^'-OCH₃), 44.89 (C-4), 42.7 (C-1), 38.5 (C-3), 36.9 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 19.7 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 946 [M+Na]⁺, HRESIMS: calcd for C₄₆H₅₇N₃O₁₇H [M+H]⁺ 924.3761, found 924.3753.

3.3.13. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26a)

White amorphous powder, yield 84% (after chromatography with petroleum ether/acetone, 1:1); mp 90 °C;

{[α]}_{D}^{26.9}

: −9.5 (c 0.26, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.79 (s, 1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.62 (s, 1H, C⁸-H), 6.40 (s, 2H, C²^', C⁶^'-CH), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 4.4 Hz, OCH₂O), 5.34 (d, 1H, J = 8.0 Hz, C⁴^'''-H), 5.29–5.26 (m, 3H, C¹^'''-H, C³^'''-H, C²^'''-H), 4.88–4.87 (m, 2H), 4.79 (d, 1H, J = 4.8 Hz, C¹-H), 4.40–4.36 (m, 1H), 4.23 (dd, 1H, J = 4.8 Hz, 10.8 Hz), 4.13–4.10 (m, 2H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.72 (s, 3H, C⁴^'-OCH₃), 3.65–3.60 (m, 12H, 3 × OCH₂CH₂O), 3.42 (dd, 1H, J = 4.8 Hz, 10.0 Hz, C²-H), 3.18–3.13 (m, 1H, C³-H), 2.39 (t, 2H, J = 7.2 Hz, COCH₂), 2.32 (t, 2H, J = 7.2 Hz, COCH₂), 2.26 (t, 2H, J = 7.2 Hz, COCH₂), 2.18 (t, 2H, J = 7.2 Hz, COCH₂), 1.71–1.62 (m, 4H, 2 × CH₂CH₃), 1.61–1.51 (m, 4H, 2 × CH₂CH₃), 0.99–0.88 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.7 (C=O), 174.0 (C=O), 173.9 (C=O), 173.8 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 146.1 (C-4^''), 140.6 (C-1^'), 138.3 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.8 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 99.0 (C-1^'''), 71.6, 71.5, 71.4, 71.2, 70.9, 70.8, 70.5, 69.8, 68.9 (C-11), 68.3, 66.8, 65.1 (C-6^''), 63.1 (C-6^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.9 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 19.6 (CH₂CH₃), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 1092 [M+Na]⁺, HRESIMS: calcd for C₅₃H₇₁N₃O₂₀H [M+H]⁺ 1070.4704, found 1070.4677.

3.3.14. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26b)

White amorphous powder, yield 85% (after chromatography with petroleum ether/acetone, 1:1); mp 74–75 °C;

{[α]}_{D}^{25.7}

: −16.1 (c 0.21, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.80 (s, 1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.63 (s, 1H, C⁸-H), 6.41 (s, 2H, C²^', C⁶^'-H), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 4.8 Hz, OCH₂O), 5.22 (d, 1H, J = 1.6 Hz, C²^'''-H), 5.12 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³^'''-H), 4.80–4.79 (m, 2H), 4.66 (s, 1H), 4.43–4.36 (m, 3H), 4.26 (dd, 1H, J = 4.0 Hz, 10.0 Hz), 3.94–3.90 (m, 1H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.72 (s, 3H, C⁴^'-OCH₃), 3.65–3.60 (m, 12H, 3 × OCH₂CH₂O), 3.43 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 3.18–3.13 (m, 1H, C³-H), 2.35–2.25 (m, 8H, 4 × COCH₂), 1.68–1.58 (m, 8H, 4 × CH₂CH₃), 0.97–0.92 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 179.0 (C-12), 175.8 (C=O), 175.0 (C=O), 174.4 (C=O), 174.0 (C=O), 154.7 (C-4^''), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 138.3 (C-1^'), 136.8 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.9 (C-5^''), 110.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 99.0 (C-1^'''), 73.1, 72.1, 71.6, 71.5, 71.4, 71.2, 70.9, 70.7, 68.2 (C-11), 66.0, 65.0 (C-6^''), 64.2 (C-6^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 37.0 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 1092 [M+Na]⁺, HRESIMS: calcd for C₅₃H₇₁N₃O₂₀H [M+H]⁺ 1070.4704, found 1070.4703.

3.3.15. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (27a)

White amorphous powder, yield 89% (after chromatography with petroleum ether/acetone, 1:1); mp 95–97 °C;

{[α]}_{D}^{26.7}

: −12.6 (c 0.29, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.79 (s, 1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.65 (s, 1H, C⁸-H), 6.38 (s, 2H, C²^', C⁶^'-H), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.98 (d, 2H, J = 5.2 Hz, OCH₂O), 5.34 (d, 1H, J = 10.0 Hz, C⁴^'''-H), 5.28–5.26 (m, 2H, C³^'''-H, C²^'''-H), 4.88–4.87 (m, 2H), 4.76 (d, 1H, J = 4.4 Hz, C¹-H), 4.41–4.37 (m, H), 4.23 (dd, 1H, J = 4.8 Hz, 10.8 Hz), 4.23–4.10 (m, 2H), 3.83–3.78 (m, 1H), 3.74 (s, 6H, C³^'-OCH₃, C⁵^'-OCH₃), 3.66–3.61 (m, 12H, 3 × OCH₂CH₂O), 3.39 (dd, 1H, J = 4.8 Hz, 10.0 Hz, C²-H), 3.18–3.13 (m, 1H, C³-H), 2.39 (t, 2H, J = 7.6 Hz, COCH₂), 2.32 (t, 2H, J = 7.6 Hz, COCH₂), 2.26 (t, 2H, J = 7.6 Hz, COCH₂), 2.18 (t, 2H, J = 7.6 Hz, COCH₂), 1.71–1.62 (m, 4H, 2 × CH₂CH₃), 1.61–1.51 (m, 4H, 2 × CH₂CH₃), 0.99–0.88 (t, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 176.0 (C-12), 174.8 (C=O), 174.0 (C=O), 173.9 (C=O), 173.8 (C=O), 150.5 (C-7), 149.2 (C-6), 148.7 (C-3^', C-5^'), 146.1 (C-4^''), 136.0 (C-1^'), 135.2 (C-9), 131.3 (C-10), 127.0 (C-4^'), 125.8 (C-5^''), 111.3 (C-5), 109.8 (C-8), 109.3 (C-2^', C-6^'), 103.3 (OCH₂O), 99.0 (C-1^'''), 71.6, 71.5, 71.4, 71.2, 70.9, 70.8, 70.5, 69.8, 68.9 (C-11), 68.3, 66.8, 65.1 (C-6^''), 63.1 (C-6^'''), 59.9 (C-2), 56.8 (3^', 5^'-OCH₃), 44.8 (C-4), 42.8 (C-1), 38.5 (C-3), 36.9 (COCH₂), 36.9 (COCH₂), 36.8 (COCH₂), 36.8 (COCH₂), 19.6 (CH₂CH₃), 19.3 (CH₂CH₃), 19.3 (CH₂CH₃), 19.2 (CH₂CH₃), 14.1 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 1078 [M+Na]⁺, HRESIMS: calcd for C₅₂H₆₉N₃O₂₀H [M+H]⁺ 1056.4547, found 1056.4533.

3.3.16. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (27b)

White amorphous powder, yield 88% (after chromatography with petroleum ether/acetone, 1:1); mp 80–82 °C;

{[α]}_{D}^{25.8}

: −26.6 (c 0.25, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.80 (s, 1H, C⁵^''-H), 6.67 (s, 1H, C⁵-H), 6.62 (s, 1H, C⁸-H), 6.41 (s, 2H, C²^', C⁶^'-H), 6.24 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 5.6 Hz, OCH₂O), 5.23 (d, 1H, J = 1.6 Hz), 5.12 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C³^'''-H), 4.80 (d, 1H, J = 1.6 Hz), 4.76 (d, 1H, J = 4.0 Hz), 4.43–4.35 (m, 3H), 4.26 (dd, 1H, J = 1.2 Hz, 5.2 Hz), 3.94–3.90 (m, 1H), 3.82–3.80 (m, 1H), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.65–3.60 (m, 12H, 3 × OCH₂CH₂O), 3.39 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 3.16–3.12 (m, 1H, C³-H), 2.35–2.24 (m, 8H, 4 × COCH₂), 1.68–1.58 (m, 8H, 4 × CH₂CH₃), 0.97–0.91 (m, 12H, 4 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 179.0 (C-12), 175.9 (C=O), 175.1 (C=O), 174.5 (C=O), 174.0 (C=O), 150.5 (C-7), 149.2 (C-6), 148.7 (C-3^', C-5^'), 146.1 (C-4^''), 136.0 (C-1^'), 135.1 (C-9), 131.4 (C-10), 126.9 (C-4^'), 125.9 (C-5^''), 111.3 (C-5), 109.8 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 99.0 (C-1^'''), 73.1, 72.1, 71.6, 71.5, 71.5, 71.2, 70.9, 70.7, 68.9 (C-11), 68.2, 66.0, 65.0, (C-6^''), 64.2 (C-6^'''), 59.9 (C-2), 56.8 (3^', 5^'-OCH₃), 44.8 (C-4), 42.7 (C-1), 38.5 (C-3), 37.0 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 36.9 (COCH₂), 19.6 (CH₂CH₃), 19.5 (CH₂CH₃), 19.4 (CH₂CH₃), 19.2 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 1078 [M+Na]⁺, HRESIMS: calcd for C₅₂H₆₉N₃O₂₀H [M+H]⁺ 1056.4547, found 1056.4509.

3.3.17. 4β-{4^''-[1^"'-(2^"',3^"',4^"'-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28a)

White amorphous powder, yield 83% (after chromatography with petroleum ether/acetone, 1:1); mp 98–99 °C;

{[α]}_{D}^{26.3}

: +20.5 (c 0.26, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.86 (s, 1H, C⁵^''-H), 6.68 (s, 1H, C⁵-H), 6.59 (s, 1H, C⁸-H), 6.41 (s, 2H, C²^', C⁶^'-H), 6.24 (d, 1H, J = 4.4 Hz, C⁴-H), 5.96 (d, 2H, J = 8.0 Hz, OCH₂O), 5.44 (t, 1H, J = 10.0 Hz, C³^"'-H), 5.13 (d, 1H, J = 3.2 Hz, C¹^"'-H), 5.00–5.96 (m, 1H, C²^"'-H), 4.77–4.73 (m, 3H), 4.65 (d, 1H, J = 4.8 Hz, C¹-H), 4.38–4.35 (m, 1H), 3.80–3.78 (m, 3H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.71 (s, 3H, C⁴^'-OCH₃), 3.43 (dd, 1H, J = 4.8 Hz, 10.4 Hz, C²-H), 3.19–3.14 (m, 1H, C³-H), 2.24–2.17 (m, 6H, 3 × COCH₂), 1.60–1.49 (m, 6H, 3 × CH₂CH₃), 0.90–0.88 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.1 (C=O), 174.0 (C=O), 173.9 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6), 144.6 (C-4^''), 138.3 (C-1^'), 136.7 (C-9), 134.7 (C-10), 127.0 (C-4^'), 126.4 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 96.1 (C-1^'''), 72.2, 70.5, 70.3, 68.9 (C-11), 61.2 (C-5^'''), 61.1 (4^'-OCH₃), 59.8 (C-2), 59.6 (C-6^''), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.8 (COCH₂), 36.7 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 861 [M+Na]⁺, HRESIMS: calcd for C₄₂H₅₁N₃O₂₅H [M+H]⁺ 838.3393, found 838.3367.

3.3.18. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28b)

White amorphous powder, yield 83% (after chromatography with petroleum ether/acetone, 1:1); mp 97–99 °C;

{[α]}_{D}^{26.7}

: −99.9 (c 0.25, Pyridine); ¹H-NMR (C₅D₅N, 500 MHz) δ 8.14 (s, 1H, C⁵^''-H), 6.86 (s, 1H, C⁵-H), 6.86 (s, 1H, C⁸-H), 6.76 (s, 2H, C²^', C⁶^'-H), 6.57 (d, 1H, J = 5.0 Hz, C⁴-H), 6.00 (d, 2H, J = 10.0 Hz, OCH₂O), 5.67 (d, 1H, J = 9.0 Hz), 5.42 (t, 1H, J = 9.0 Hz, C³^'''-H), 5.33–5.29 (m, 1H), 5.14–5.12 (m, 2H), 5.10 (d, 1H, J = 8.0 Hz, C¹^'''-H), 5.01 (d, 1H, J = 5.0 Hz, C¹-H), 5.06–5.04 (m, 2H), 4.42 (t, 1H, J = 8.0 Hz), 4.28 (dd, 1H, J = 5.0 Hz, 10.0 Hz), 3.82 (s, 6H, C³^', C⁵^'-OCH₃), 3.78 (s, 3H, C⁴^'-OCH₃), 3.60–3.58 (m, 1H, C²-H), 3.45–3.42 (m, 1H, C³-H), 2.30–2.24 (m, 6H, 3 × COCH₂) 1.60–1.54 (m, 6H, 3 × CH₂CH₃), 0.83–0.78 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (C₅D₅N, 100 MHz) δ 174.0 (C-12), 172.6 (C=O), 172.6 (C=O), 172.3 (C=O), 153.5 (C-3^', C-5^'), 149.5 (C-7), 148.3 (C-6), 144.6 (C-4^''), 138.3 (C-1^'), 136.7 (C-9), 134.0 (C-10), 126.4 (C-4^'), 124.9 (C-5^''), 110.7 (C-5), 109.4 (C-8), 109.2 (C-2^', C-6^'), 102.5 (OCH₂O), 100.5 (C-1^'''), 72.1, 71.4, 69.4, 67.9 (C-11), 62.7 (C-5^'''), 62.6 (C-6^''), 60.6 (4^'-OCH₃), 58.8 (C-2), 56.2 (3^', 5^'-OCH₃), 44.3 (C-4), 41.9 (C-1), 38.0 (C-3), 36.0 (COCH₂), 36.0 (COCH₂), 35.9 (COCH₂), 18.7 (CH₂CH₃), 18.6 (CH₂CH₃), 18.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃); ESIMS: m/z 860 [M+Na]⁺, HRESIMS: calcd for C₄₂H₅₁N₃O₁₅H [M+H]⁺ 838.3393, found 838.3369.

3.3.19. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (29a)

White amorphous powder, yield 84% (after chromatography with petroleum ether/acetone, 1:1); mp 200–203 °C;

{[α]}_{D}^{26.6}

: −27.3 (c 0.25, Pyridine); ¹H-NMR (C₅D₅N, 400 MHz) δ 8.30 (s, 1H, C⁵^''-H), 6.87 (s, 1H, C⁵-H), 6.85 (s, 1H, C⁸-H), 6.81 (s, 2H, C²^', C⁶^'-H), 6.56 (d, 1H, J = 4.8 Hz, C⁴-H), 6.03–5.96 (m, 3H, OCH₂O, C⁴^'''-H), 5.64 (d, 1H, J = 4.0 Hz, C¹^'''-H), 5.41–5.35 (m, 1H, C³^'''-H), 5.23 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²^'''-H), 5.08–5.05 (m, 2H), 5.02 (d, 1H, J = 5.0 Hz, C¹-H), 4.45 (t, 1H, J = 8.0 Hz), 4.01–3.94 (m, 3H), 3.80 (dd, 1H, J = 5.0 Hz, 10.0 Hz, C²-H), 3.72 (s, 6H, C³^', C⁵^'-OCH₃), 3.46 (t, 1H, J = 10.0 Hz, C³-H), 2.32–2.20 (m, 6H, 3 × COCH₂), 1.62–1.50 (m, 6H, 3 × CH₂CH₃), 0.83–0.77 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (C₅D₅N, 100 MHz) δ 174.1 (C-12), 172.8 (C=O), 172.7 (C=O), 172.6 (C=O), 149.4 (C-7), 148.8 (C-3^', C-5^'), 148.2 (C-6), 144.0 (C-4^''), 137.4 (C-1^'), 134.5 (C-9), 130.0 (C-10), 126.4 (C-5^''), 125.4 (C-4^'), 110.7 (C-5), 109.7 (C-2^', C-6^'), 109.3 (C-8), 102.4 (OCH₂O), 95.4 (C-1^'''), 71.5, 69.7, 69.6, 67.9 (C-11), 60.9 (C-5^'''), 59.1 (C-2), 58.9 (C-6^''), 56.5 (3^', 5^'-OCH₃), 44.2 (C-4), 42.1 (C-1), 37.9 (C-3), 36.1 (COCH₂), 36.0 (COCH₂), 35.9 (COCH₂), 18.7 (CH₂CH₃), 18.6 (CH₂CH₃), 18.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃); ESIMS: m/z 846 [M+Na]⁺, HRESIMS: calcd for C₄₁H₄₉N₃O₁₅H [M+H]⁺ 824.3236, found 824.3226.

3.3.20. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (29b)

White amorphous powder, yield 82% (after chromatography with petroleum ether/acetone, 1:1); mp 100–101 °C;

{[α]}_{D}^{26.7}

: −121.4 (c 0.19, Pyridine); ¹H-NMR (C₅D₅N, 400 MHz) δ 8.14 (s, 1H, C⁵^''-H), 6.87 (s, 1H, C⁵-H), 6.83 (s, 1H, C⁸-H), 6.80 (s, 2H, C²^', C⁶^'-H), 6.56 (d, 1H, J = 4.8 Hz, C⁴-H), 6.00–5.97 (m, 2H, OCH₂O), 5.68 (t, 1H, J = 8.8 Hz, C³^'''-H), 5.46–5.42 (m, 1H, C⁴^'''-H), 5.35–5.30 (m, 1H, C²^'''-H), 5.15–5.14 (m, 2H), 5.11 (d, 1H, J = 7.2 Hz, C¹^'''-H), 5.00–4.99 (m, 3H), 4.46 (t, 1H, J = 8.0 Hz), 4.29 (dd, 1H, J = 5.0 Hz, 10.0 Hz), 3.72 (s, 6H, C³^', C⁵^'-OCH₃), 3.67–3.58 (m, 1H, C²-H), 3.44–3.42 (m, 1H, C³-H), 2.31–2.21 (m, 6H, 3 × COCH₂), 1.61–1.52 (m, 6H, 3 × CH₂CH₃), 0.85–0.78 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (C₅D₅N, 100 MHz) δ 174.1 (C-12), 172.7 (C=O), 172.6 (C=O), 172.3 (C=O), 149.5 (C-7), 148.8 (C-3^', C-5^'), 148.2 (C-6), 144.6 (C-4^''), 137.4 (C-1^'), 134.5 (C-9), 130.0 (C-10), 126.3 (C-5^''), 124.9 (C-4^'), 110.8 (C-5), 109.7 (C-2^', C-6^'), 109.3 (C-8), 102.4 (OCH₂O), 100.5 (C-1^'''), 72.1, 71.4, 69.4, 67.9 (C-11), 62.7 (C-5^'''), 62.6 (C-6^''), 58.9 (C-2), 56.5 (3^', 5^'-OCH₃), 44.1 (C-4), 42.1 (C-1), 38.0 (C-3), 36.1 (COCH₂), 36.0 (COCH₂), 35.9 (COCH₂), 18.7 (CH₂CH₃), 18.6 (CH₂CH₃), 18.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃), 13.6 (CH₂CH₃); ESIMS: m/z 860 [M+Na]⁺, HRESIMS: calcd for C₄₂H₅₁N₃O₁₅H [M+H]⁺ 838.3393, found 838.3369.

3.3.21. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30a)

White amorphous power, yield 83% (after chromatography with petroleum ether/acetone, 1:1); mp 84 °C;

{[α]}_{D}^{26.5}

: +12.2 (c 0.28, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.78 (s, 1H, C⁵^''-H), 6.68 (s, 1H, C⁵-H), 6.60 (s, 1H, C⁸-H), 6.41 (s, 2H, C²^', C⁶^'-H), 6.25 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 5.2 Hz, OCH₂O), 5.47 (t, 1H, J = 10.0 Hz, C³^'''-H), 5.06–5.04 (m, 1H, C⁴^'''-H), 4.96–4.94 (m, 1H, C²^'''-H), 4.84 (d, 1H, J = 4.0 Hz, C¹^'''-H), 4.81 (d, 1H, J = 4.0 Hz, C¹-H), 4.79–4.78 (m, 2H), 4.39–4.34 (m, 1H), 3.80–3.78 (m, 3H), 3.73 (s, 6H, C³^', C⁵^'-OCH₃), 3.71 (s, 3H, C⁴^'-OCH₃), 3.65–3.59 (m, 12H, 3 × OCH₂CH₂O), 3.41 (dd, 1H, J = 4.0 Hz, 10.8 Hz, C²-H), 3.17–3.12 (m, 1H, C³-H), 2.27–2.23 (m, 6H, 3 × COCH₂), 1.60–1.53 (m, 6H, 3 × CH₂CH₃), 0.92–0.87 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.7 (C-12), 174.1 (C=O), 174.1 (C=O), 173.9 (C=O), 154.0 (C-3^', C-5^'), 150.5 (C-7), 149.3 (C-6), 146.1 (C-4^''), 138.3 (C-1^'), 136.7 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.8 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 97.3 (C-1^'''), 72.2, 71.7, 71.6, 71.5, 71.3, 71.0, 70.7, 70.5, 68.9 (C-11), 68.5, 65.1 (C-5^'''), 61.2 (4^'-OCH₃), 59.8 (C-2), 59.4 (C-6^''), 56.7 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.9 (COCH₂), 36.8 (COCH₂), 36.6 (COCH₂), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃); ESIMS: m/z 992 [M+Na]⁺, HRESIMS: calcd for C₄₈H₆₃N₃O₁₈H [M+H]⁺ 970.4179, found 970.4167.

3.3.22. 4β-{4^''-[1^"'-(2^"',3^"',4^"'-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30b)

White amorphous powder, yield 85% (after chromatography with petroleum ether/acetone, 1:1); mp 88–90 °C;

{[α]}_{D}^{26.5}

: −45.9 (c 0.22, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.80 (s, 1H, C⁵^''-H), 6.69 (s, 1H, C⁵-H), 6.62 (s, 1H, C⁸-H), 6.42 (s, 2H, C²^', C⁶^'-H), 6.26 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 5.6 Hz, OCH₂O), 5.24 (t, 1H, J = 9.2 Hz, C³^"'-H), 4.89–4.86 (m, 2H, C²^"'-H, C⁴^"'-H), 4.80 (d, 1H, J = 5.2 Hz, C¹-H), 4.64 (d, 1H, J = 8.0 Hz, C¹^"'-H), 4.63–4.62 (m, 2H), 4.41–4.36 (m, 1H), 4.06–4.02 (m, 1H), 3.88–3.83 (m, 1H), 3.81–3.79 (s, 2H, C⁵^'''-CH₂), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.72 (s, 3H, C⁴^'-OCH₃), 3.66–3.3.60 (m, 12H, 3 × OCH₂CH₂O), 3.48–3.43 (m, 1H, C²-H), 3.18–3.14 (m, 1H, C³-H), 2.30–2.20 (m, 6H, 3 × COCH₂), 1.61–1.53 (m, 6H, 3 × CH₂CH₃), 0.91–0.89 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 175.8 (C-12), 174.0 (C=O), 174.0 (C=O), 173.7 (C=O), 154.0 (C-3^', C-5^'), 150.6 (C-7), 149.3 (C-6),146.1 (C-4^''), 138.3 (C-1^'), 136.7 (C-9), 134.8 (C-10), 127.0 (C-4^'), 125.8 (C-5^''), 111.2 (C-5), 109.9 (C-8), 109.4 (C-2^', C-6^'), 103.3 (OCH₂O), 102.3 (C-1^'''), 73.1, 72.3, 71.6, 71.5, 71.4, 70.9, 70.3, 69.9 (C-11), 65.1 (C-5^'''), 63.3 (C-6^''), 61.6 (4^'-OCH₃), 59.8 (C-2), 56.6 (3^', 5^'-OCH₃), 44.9 (C-4), 42.5 (C-1), 38.6 (C-3), 36.9 (COCH₂), 36.8 (COCH₂), 36.7 (COCH₂), 19.4 (CH₂CH₃), 19.4 (CH₂CH₃), 19.3 (CH₂CH₃), 14.0 (CH₂CH₃), 14.0 (CH₂CH₃), 13.9 (CH₂CH₃); ESIMS: m/z 992 [M+Na]⁺, HRESIMS: calcd for C₄₈H₆₃N₃O₁₈H [M+H]⁺ 970.4179, found 970.4162.

3.3.23. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (31a)

White amorphous powder, yield 86% (after chromatography with petroleum ether/acetone, 1:1); mp 87–88 °C;

{[α]}_{D}^{26.2}

: +7.1 (c 0.22, CH₃OH); ¹H-NMR (CD₃OD, 400 MHz) δ 7.77 (s, 1H, C⁵^''-H), 6.67 (s, 1H, C⁵-H), 6.63 (s, 1H, C⁸-H), 6.38 (s, 2H, C²^', C⁶^'-H), 6.24 (d, 1H, J = 4.4 Hz, C⁴-H), 5.97 (d, 2H, J = 5.6 Hz, OCH₂O), 5.47 (t, 1H, J = 10.0 Hz, C³^'''-H), 5.06 (d, 1H, J = 3.2 Hz, C¹^'''-H), 4.97–4.94 (m, 1H, C²^'''-H), 4.85–4.84 (m, 1H, C⁴^'''-H), 4.81 (d, 1H, J = 4.0 Hz, C¹-H), 4.76–4.73 (m, 2H), 4.37 (t, 1H, J = 7.2 Hz), 3.74 (s, 6H, C³^', C⁵^'-OCH₃), 3.66–3.60 (m, 12H, 3 × OCH₂CH₂O), 3.39 (dd, 1H, J = 4.0 Hz, 10.0 Hz, C²-H), 3.15 (t, 1H, J = 10.0 Hz, C³-H), 2.29–2.22 (m, 6H, 3 × COCH₂), 1.61–1.54 (m, 6H, 3 × CH₂CH₃), 0.91–0.87 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (CD₃OD, 100 MHz) δ 174.4 (C-12), 172.6 (C=O), 172.5 (C=O), 172.4 (C=O), 149.0 (C-7), 147.7 (C-6), 147.2 (C-3^', C-5^'), 144.6 (C-4^''), 134.5 (C-1^'), 133.6 (C-9), 129.8 (C-10), 125.3 (C-4^'), 124.2 (C-5^''), 109.7 (C-5), 108.3 (C-8), 107.8 (C-2^', C-6^'), 101.7 (OCH₂O), 95.7 (C-1^'''), 70.6, 70.1, 70.0, 69.7, 69.4, 69.1, 69.0, 67.4 (C-11), 67.0, 63.5 (C-5^'''), 58.3 (C-2), 57.8 (C-6^''), 55.2 (3^', 5^'-OCH₃), 43.2 (C-4), 41.2 (C-1), 37.0 (C-3), 35.3 (COCH₂), 35.2 (COCH₂), 35.1 (COCH₂), 17.9 (CH₂CH₃), 17.8 (CH₂CH₃), 17.8 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃), 12.4 (CH₂CH₃); ESIMS: m/z 978 [M+Na]⁺, HRESIMS: calcd for C₄₇H₆₁N₃O₁₈H [M+H]⁺ 956.4023, found 956.4015.

3.3.24. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (31b)

White amorphous powder, yield 87% (after chromatography with petroleum ether/acetone, 1:1); mp 79–80 °C;

{[α]}_{D}^{26.6}

: −93.4 (c 0.29, Pyridine); ¹H-NMR (C₅D₅N, 400 MHz) δ 8.11 (s, 1H, C⁵^''-H), 6.86 (s, 1H, C⁵-H), 6.85 (s, 1H, C⁸-H), 6.80 (s, 2H, C²^', C⁶^'-H), 6.53 (d, 1H, J = 4.8 Hz, C⁴-H), 5.97 (d, 2H, J = 6.8 Hz, OCH₂O), 5.69 (t, 1H, J = 9.2 Hz, C³^'''-H), 5.44–5.40 (m, 1H, C⁴^'''-H), 5.35–5.30 (m, 1H, C²^'''-H), 4.98 (d, 1H, J = 4.8 Hz, C¹-H), 4.87 (d, 1H, J = 7.2 Hz, C¹^'''-H), 4.84 (s, 2H), 4.44 (t, 1H, J = 8.0 Hz), 4.28 (dd, 1H, J = 6.0 Hz, 10.0 Hz), 4.01–3.96 (m, 1H), 3.78–3.75 (m, 1H), 3.72 (s, 6H, C³^', C⁵^'-OCH₃), 3.63–3.57 (m, 12H, 3 × OCH₂CH₂O), 3.45–3.41 (m, 1H, C³-H), 2.38–2.26 (m, 6H, 3 × COCH₂), 1.66–1.52 (m, 6H, 3 × CH₂CH₃), 0.87–0.80 (m, 9H, 3 × CH₂CH₃); ¹³C-NMR (C₅D₅N, 100 MHz) δ 174.1 (C-12), 172.7 (C=O), 172.6 (C=O), 172.3 (C=O), 148.7 (C-7), 148.2 (C-3^', C-5^'), 148.2 (C-6), 145.7 (C-4^''), 137.4 (C-1^'), 134.5 (C-9), 130.0 (C-10), 126.4 (C-4^'), 124.5 (C-5^''), 110.7 (C-5), 109.7 (C-2^', C-6^'), 109.3 (C-8), 102.4 (OCH₂O), 101.5 (C-1^'''), 72.2, 71.5, 70.8, 70.7, 70.5, 70.4, 69.5, 69.0, 67.9 (C-11), 65.0 (C-5^'''), 62.6 (C-2), 58.8 (C-6^''), 56.5 (3^', 5^'-OCH₃), 44.1 (C-4), 42.1 (C-1), 37.9 (C-3), 36.1 (COCH₂), 36.1 (COCH₂), 36.0 (COCH₂), 18.7 (CH₂CH₃), 18.7 (CH₂CH₃), 18.6 (CH₂CH₃), 13.7 (CH₂CH₃), 13.7 (CH₂CH₃), 13.6 (CH₂CH₃); ESIMS: m/z 978 [M+Na]⁺, HRESIMS: calcd for C₄₇H₆₁N₃O₁₈H [M+H]⁺ 956.4023, found 956.4007.

3.4. Cell Culture and Cytotoxicity Assay

The following human tumor cell lines were used: HL-60, SMMC-7721, A-549, MCF-7, and SW480. All the cells were cultured in RMPI-1640 or DMEM medium (Hyclone, Logan, UT, USA), supplemented with 10% fetal bovine serum (Hyclone) at 37 °C in a humidified atmosphere with 5% CO₂. Cell viability was assessed by conducting colorimetric measurements of the amount of insoluble formazan formed in living cells based on the reduction of 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (Sigma, St. Louis, MO, USA). Briefly, adherent cells (100 μL) were seeded into each well of a 96-well cell culture plate and allowed to adhere for 12 h before drug addition, while suspended cells were seeded just before drug addition, both with an initial density of 1 × 10⁵ cells/mL in 100 μL of medium. Each tumor cell line was exposed to the test compound at various concentrations in triplicate for 48 h. After the incubation, MTT (100 μg) was added to each well, and the incubation continued for 4 h at 37 °C. The cells lysed with SDS (200 μL) after removal of 100 μL of medium. The optical density of lysate was measured at 595 nm in a 96-well microtiter plate reader (Bio-Rad 680, Hercules, CA, USA). The IC₅₀ value of each compound was calculated by Reed and Muench’s method [32].

4. Conclusions

A series of novel 4β-triazole-podophyllotoxin glycoconjugates have been synthesized and screened for anticancer activity against a panel of five human cancer cell lines. The majority of the compounds display moderate to weak cytotoxicity against all five cancer cell lines. Among the synthesized compounds, compound 21a shows the highest potency of anticancer activity, with IC₅₀ values ranging from 0.49 to 6.70 μM, which is more potent than the control drug etoposide (2). Compound 21a is derived from D-galactose, having a hydroxyl group at the 4'-postion of the E ring, an α-glycosidic linkage, and no linking spacer between the galactose moiety and the 1,2,3-triazole residue. These findings will be useful for the further research and development of glycosylated podophyllotoxin derivatives as antitumour agents.

Acknowledgments

This work was financially supported by the Fund of State Key Laboratory of Phytochemistry and Plant Resource in West China (P2010-KF07). The authors thank the staff of analytical group of the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, for measurements of all spectra.

Author Contributions

The list authors contributed to this work as follows: Jun Zhou, Zhong-Tao Ding, and Zi-Hua Jiang conceived and designed the study. Cheng-Ting Zi, and Zhen-Hua Liu performed the experiments. Gen-Tao Li, and Yan Li evaluated the biological activity against five human cancer cell lines. Cheng-Ting Zi wrote the paper. Zi-Hua Jiang, and Jiang-Miao Hu edited and revised the manuscript.

Conflicts of Interest

The authors declare no conflict of interest.

References

MacRae, W.D.; Hudson, J.B.; Towers, B.H. The antiviral action of lignans. Planta Med. 1989, 55, 531–535. [Google Scholar] [CrossRef] [PubMed]
Gordaliza, M.; García, P.A.; Miguel del Corral, J.M.; Castro, M.A.; Gómez-Zurita, M.A. Podophyllotoxin: Distribution, sources, applications and new cytotoxic derivatives. Toxicon 2004, 44, 441–459. [Google Scholar] [CrossRef] [PubMed]
Jardine, I. Podophyllotoxins. In Anticancer Agents Based on Natural Product Models; Cassady, J.M., Douros, J.D., Eds.; Academic Press: New York, NY, USA, 1980; pp. 319–351. [Google Scholar]
Bohlin, L.; Rosén, B. Podophyllotoxin derivatives: Drug discovery and development. Drug Discov. Today 1996, 1, 343–351. [Google Scholar] [CrossRef]
Stahelin, H. Activity of a new glycosidic lignan derivative (VP 16-213) related to podophyllotoxin in experimental tumors. Eur. J. Cancer 1973, 9, 215–221. [Google Scholar] [CrossRef] [PubMed]
Lee, K.H.; Beers, S.A.; Mori, M.; Wang, Z.Q.; Kuo, Y.H.; Li, L.; Liu, S.Y.; Cheng, J.Y.; Han, F.S.; Cheng, Y.C. New 4-hydroxylated and 4-halogenated anilino derivatives of 4'-demet hylepipodophyllotoxin as potent inhibitors of human DNA Topoisomerase II. J. Med. Chem. 1990, 33, 1364–1368. [Google Scholar] [CrossRef] [PubMed]
Stahelin, H.; von Wartburg, A. From podophyllotoxin glucoside to etoposide. Prog. Drug Res. 1989, 33, 169–266. [Google Scholar] [PubMed]
Doyle, T.W. The chemistry of etoposide. In Etoposide (VP-16) Current Status and New Developments; Issell, B.F., Muggia, F.M., Carter, S.K., Eds.; Academic Press: New York, NY, USA, 1984; pp. 15–32. [Google Scholar]
Wang, Z.Q.; Kuo, Y.H.; Schnur, J.; Bowen, J.P.; Liu, S.Y.; Han, F.S.; Chang, J.Y.; Cheng, Y.C.; Lee, K.H. New 4β-arylamino derivatives of 4'-O -demethylepipodophyllotoxin and related compounds as potent Inhibitors of human DNA Topoisomerase II. J. Med. Chem. 1990, 33, 2660–2666. [Google Scholar] [CrossRef]
Issell, B.F. The podophyllotoxin derivatives VP16-213 and VM26. Cancer Chemother. Pharmacol. 1982, 7, 73–80. [Google Scholar] [PubMed]
Budman, D.R. Early studies of etoposide phosphate, a water-soluble prodrug. Semin. Oncol. 1996, 23, 8–14. [Google Scholar] [PubMed]
Hande, K.R.; Krozely, M.G.; Greco, F.A.; Hainsworth, J.D.; Johnson, D.H. Bioavailability of low-dose oral etoposide. Semin. Oncol. 1993, 11, 374–377. [Google Scholar]
Van Maanen, J.M.S.; Retel, J.; de Vries, J.; Pinedo, H.M. Mechanism of action of antitumor drug etoposide: A review. J. Natl. Cancer Inst. 1988, 80, 1526–1533. [Google Scholar]
Hainsworth, J.D.; Williams, S.D.; Einhorn, L.H.; Birch, R.; Greco, F.A. Successful treatment of resistant germinal neoplasms with VP-16 and cisplatin: Results of a southeastern cancer study group trial. J. Clin. Oncol. 1985, 3, 666–671. [Google Scholar] [PubMed]
Passarella, D.; Peretto, B.; Yepes, R.B.; Cappelletti, G.; Cartelli, D.; Ronchi, C.; Snaith, J.; Fontana, G.; Danieli, B.; Borlak, J. Synthesis and biological evaluation of novel thiocolchicine-podophyllotoxin conjugates. Eur. J. Med. Chem. 2010, 45, 219–266. [Google Scholar] [CrossRef] [PubMed]
Sackett, D.L. Podophyllotoxin, steganacin and combretastatin: Natural products that bind at the colchicine site of tubulin. Pharmacol. Ther. 1993, 59, 163–228. [Google Scholar] [CrossRef] [PubMed]
Reddy, P.B.; Paul, D.V.; Agrawal, S.K.; Saxena, A.K.; Kumar, H.M.S.; Qazi, G.N. Design, synthesis, and biological testing of 4β-[(4-substituted)-1,2,3-triazol-1-yl]podophyllotoxin analogues as antitumor agents. Arch. Pharm. 2008, 341, 126–131. [Google Scholar] [CrossRef]
Chari, R.V.J.; Miller, M.L.; Widdison, W.C. Antibody-drug conjugates: An emerging concept in cancer therapy. Angew. Chem. Int. Ed. 2014, 53, 3796–3827. [Google Scholar] [CrossRef]
Biju, V. Chemical modifications and bioconjugate reactions of nanomaterials for sensing, imaging, drug delivery and therapy. Chem. Soc. Rev. 2014, 43, 744–764. [Google Scholar] [CrossRef] [PubMed]
Nakanishi, W.; Minamia, K.; Shresthaa, L.K.; Ji, Q.; Hill, J.P.; Ariga, K. Bioactive nanocarbon assemblies: Nanoarchitectonics and applications. Nano Today 2014, 9, 378–394. [Google Scholar] [CrossRef]
Berim, A.; Ebel, R.; Schneider, B.; Petersen, M. UDP-glucose:(6-methoxy)podophyllotoxin 7-O-glucosyltransferase from suspension cultures of Linum nodiflorum. Phytochemistry 2008, 69, 374–381. [Google Scholar] [CrossRef] [PubMed]
Stoll, A.; Renz, J.; Wartburg, A.V. The isolation of podophyllotoxin glucoside. J. Am. Chem. Soc. 1954, 76, 3103–3104. [Google Scholar] [CrossRef]
Keller-Juslén, C.; Kuhn, M.; von Wartburg, A. Synthesis and antimitotic activity of glycosidic lignan derivatives related to podophyllotoxin. J. Med. Chem. 1971, 14, 936–940. [Google Scholar] [CrossRef] [PubMed]
Zi, C.T.; Xu, F.Q.; Li, G.T.; Li, Y.; Ding, Z.T.; Zhou, J.; Jiang, Z.H.; Hu, J.M. Synthesis and anticancer activity of glucosylated podophyllotoxin derivatives linked via 4β-Triazole rings. Molecules 2013, 18, 1420–1430. [Google Scholar] [CrossRef]
Krivopalov, V.P.; Shkurko, O.P. 1,2,3-Triazole and its derivatives. Development of methods for the formation of the triazole ring. Russ. Chem. Rev. 2005, 74, 339–379. [Google Scholar] [CrossRef]
Shafran, E.A.; Bakulev, V.A.; Rozin, Y.A.; Shafran, Y.M. Condensed 1,2,3-triazoles (review). Chem. Heterocycl. Compd. 2008, 44, 1040–1069. [Google Scholar] [CrossRef]
Huisgen, R. 1,3-Dipolar cycloadditions. Proc. Chem. Soc. 1961, 6, 357–369. [Google Scholar]
Arioli, F.; Borrelli, S.; Colombo, F.; Falchi, F.; Filippi, I.; Crespan, E.; Naldini, A.; Scalia, G.; Silvani, A.; Maga, G.; et al. N-[2-Methyl-5-(triazol-1-yl)phenyl]pyrimidin-2-amine as a scaffold for the synthesis of inhibitors of Bcr-Abl. Chem. Med. Chem. 2011, 6, 2009–2018. [Google Scholar] [CrossRef] [PubMed]
Michel, O.; Jan Ravoo, B. Carbohydrate microarrays by microcontact “Click” chemistry. Langmuir 2008, 24, 12116–12118. [Google Scholar] [CrossRef] [PubMed]
Roy, B.; Mukhopadhyay, B. Sulfuric acid immobilized on silica: An excellent catalyst for Fischer type glycosylation. Tetrahedron Lett. 2007, 48, 3783–3787. [Google Scholar] [CrossRef]
Kouroumounis, G.K.; Massy-Westropp, R.A.; Sefton, M.A.; Williams, P.J. Synthesis of glucosides related to grape and wine aroma precursors. J. Agric. Food Chem. 1995, 43, 974–980. [Google Scholar] [CrossRef]
Kolb, H.C.; Finn, M.G.; Sharpless, K.B. Click chemistry: Diverse chemical function from a few good reactions. Angew. Chem. Int. Ed. 2001, 40, 2004–2021. [Google Scholar] [CrossRef]
Saravanakumar, R.; Ramkumar, V.; Sankararaman, S. Synthesis and structural characterization of cis isomer of 1,2,3-triazol-5-ylidene based palladium complexes. J. Organomet. Chem. 2013, 736, 36–41. [Google Scholar] [CrossRef]
Zhou, X.M.; Wang, Z.Q.; Chang, J.Y.; Chen, H.X.; Cheng, Y.C.; Lee, K.H. New 4-substituted benzylamine and benzyl ether derivatives of 4'-O-demethylepipodophyollotoxin as potent inhibitors of human DNA Topoisomerase II. J. Med. Chem. 1991, 34, 3346–3350. [Google Scholar] [CrossRef] [PubMed]
Tae, H.S.; Hines, J.; Schneekloth, A.R.; Crews, C.M. Total synthesis and biological evaluation of tyroscherin. Org. Lett. 2010, 12, 4308–4311. [Google Scholar] [CrossRef] [PubMed]
Chen, S.W.; Wang, Y.H.; Jin, Y.; Tian, X.; Zheng, Y.T.; Luo, D.Q.; Tu, Y.Q. Synthesis and anti-HIV-1 activities of novel podophyllotoxin derivatives. Bioorg. Med. Chem. Lett. 2007, 17, 2091–2095. [Google Scholar] [CrossRef] [PubMed]
Reed, L.J.; Muench, H. A simple method of estimating fifty percent endpoints. Am. J. Hyg. 1938, 27, 493–497. [Google Scholar]

Sample Availability: Samples of the podophyllotoxin are available from the authors.

© 2015 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license ( http://creativecommons.org/licenses/by/4.0/).

Share and Cite

MDPI and ACS Style

Zi, C.-T.; Liu, Z.-H.; Li, G.-T.; Li, Y.; Zhou, J.; Ding, Z.-T.; Hu, J.-M.; Jiang, Z.-H. Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives. Molecules 2015, 20, 3255-3280. https://doi.org/10.3390/molecules20023255

AMA Style

Zi C-T, Liu Z-H, Li G-T, Li Y, Zhou J, Ding Z-T, Hu J-M, Jiang Z-H. Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives. Molecules. 2015; 20(2):3255-3280. https://doi.org/10.3390/molecules20023255

Chicago/Turabian Style

Zi, Cheng-Ting, Zhen-Hua Liu, Gen-Tao Li, Yan Li, Jun Zhou, Zhong-Tao Ding, Jiang-Miao Hu, and Zi-Hua Jiang. 2015. "Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives" Molecules 20, no. 2: 3255-3280. https://doi.org/10.3390/molecules20023255

Article Menu

Design, Synthesis, and Cytotoxicity of Perbutyrylated Glycosides of 4β-Triazolopodophyllotoxin Derivatives

Abstract

1. Introduction

2. Results and Discussion

2.1. Chemical Synthesis

2.2. Evaluation of Biological Activity

3. Experimental Section

3.1. General

3.2. General Procedure for the Synthesis of Compounds 12a/b–17a/b

3.2.1. 2-Propyn-1-yl-per-O-butyryl-α-d-galactopyranose (12a)

3.2.2. 2-Propyn-1-yl-per-O-butyryl-β-d-galactopyranose (12b)

3.2.3. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-galactopyranoside (13a)

3.2.4. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-galactopyranoside (13b)

3.2.5. 2-Propyn-1-yl-per-O-butyryl-α-d-mannopyranoside (14a)

3.2.6. 2-Propyn-1-yl-per-O-butyryl-β-d-mannopyranoside (14b)

3.2.7. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-mannopyranoside (15a)

3.2.8. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-mannopyranoside (15b)

3.2.9. 2-Propyn-1-yl-per-O-butyryl-α-d-xylopyranoside (16a)

3.2.10. 2-Propyn-1-yl-per-O-butyryl-β-d-xylopyranoside (16b)

3.2.11. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-α-d-xylopyranoside (17a)

3.2.12. 2-[2-[2-(2-Propyn-1-yloxy)ethoxy]ethoxy-per-O-butyryl-β-d-xylopyranoside (17b)

3.3. Click Chemistry-General Procedure

3.3.1. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20a)

3.3.2. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20b)

3.3.3. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (21a)

3.3.4. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (21b)

3.3.5. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22a)

3.3.6. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22b)

3.3.7. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (23a)

3.3.8. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (23b)

3.3.9. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24a)

3.3.10. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24b)

3.3.11. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (25a)

3.3.12. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (25b)

3.3.13. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26a)

3.3.14. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26b)

3.3.15. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (27a)

3.3.16. 4β-{4''-[1'''-(2''',3''',4''',6'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (27b)

3.3.17. 4β-{4''-[1"'-(2"',3"',4"'-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28a)

3.3.18. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28b)

3.3.19. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (29a)

3.3.20. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4'-demethylpodophyllotoxin (29b)

3.3.21. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30a)

3.3.22. 4β-{4''-[1"'-(2"',3"',4"'-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30b)

3.3.23. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (31a)

3.3.24. 4β-{4''-[1'''-(2''',3''',4'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4'-demethylpodophyllotoxin (31b)

3.4. Cell Culture and Cytotoxicity Assay

4. Conclusions

Acknowledgments

Author Contributions

Conflicts of Interest

References

Share and Cite

Article Metrics

Article Access Statistics

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

3.3.1. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20a)

3.3.2. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (20b)

3.3.3. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (21a)

3.3.4. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (21b)

3.3.5. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22a)

3.3.6. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (22b)

3.3.7. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (23a)

3.3.8. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-galactopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (23b)

3.3.9. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24a)

3.3.10. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (24b)

3.3.11. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (25a)

3.3.12. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (25b)

3.3.13. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26a)

3.3.14. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (26b)

3.3.15. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-α-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (27a)

3.3.16. 4β-{4^''-[1^'''-(2^''',3^''',4^''',6^'''-Tetra-O-butyryl-β-d-mannopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (27b)

3.3.17. 4β-{4^''-[1^"'-(2^"',3^"',4^"'-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28a)

3.3.18. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-podophyllotoxin (28b)

3.3.19. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (29a)

3.3.20. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-1,2,3-triazol-1-yl]}-4-deoxy-4^'-demethylpodophyllotoxin (29b)

3.3.21. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30a)

3.3.22. 4β-{4^''-[1^"'-(2^"',3^"',4^"'-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxypodophyllotoxin (30b)

3.3.23. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-α-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (31a)

3.3.24. 4β-{4^''-[1^'''-(2^''',3^''',4^'''-Tri-O-butyryl-β-d-xylopyranosyloxy)-3,6,9-trioxadec-10-yl]-1,2,3-triazol-1-yl}-4-deoxy-4^'-demethylpodophyllotoxin (31b)