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Article

A Mild and Regioselective Ring-Opening of Aziridines with Acid Anhydride Using TBD or PS-TBD as a Catalyst

by
Satoru Matsukawa
* and
Yasutaka Mouri
Department of Science Education, Faculty of Education, Ibaraki University, Ibaraki 310-8512, Japan
*
Author to whom correspondence should be addressed.
Molecules 2015, 20(10), 18482-18495; https://doi.org/10.3390/molecules201018482
Submission received: 2 September 2015 / Revised: 22 September 2015 / Accepted: 23 September 2015 / Published: 9 October 2015
(This article belongs to the Special Issue Brønsted Base Catalysis in Organic Synthesis)
Browse Figures
Versions Notes

Abstract

:
The ring-opening of N-tosylaziridines with various acid anhydrides catalyzed by 5 mol % of 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) afforded the corresponding β-amino esters in excellent yields under mild reaction conditions. Polymer-supported catalyst, PS-TBD also acts as a good catalyst for this reaction. PS-TBD was easily recovered and reused with minimal loss of activity.

Graphical Abstract

1. Introduction

Aziridines are very useful intermediates for the synthesis of numerous nitrogen-containing biologically active compounds [1,2,3]. Therefore, nucleophilic ring-opening of aziridines by various approaches has been widely examined and developed [4,5,6,7,8,9,10]. β-amino alcohols, which can be synthesized from the nucleophilic ring-opening reactions of aziridines are useful intermediates in organic synthesis [4,7]. The ring-opening of aziridines with water is the most common method to prepare free β-amino alcohols. Many examples are reported to this day [11,12,13,14,15,16,17,18,19,20,21,22]. On the other hand, selectively protected β-amino alcohols are convenient intermediate to synthesize highly functionalized products. Therefore, the ring-opening reaction of aziridines with acid or acid anhydrides as the nucleophiles have been recently studied. To date, reactions using indium rtiflate [23], tributylphosphine [24], scandium triflate [25], ammonium-12-molybdophosphate [26], N-heterocyclic carbine [27] and tetrabutyl ammonium bromide [28] as catalysts have been reported. To develop of a more efficient reaction, we examined the use of TBD (1,5,7-Triazabicyclo[4,4,0]dec-5-ene) as a catalyst.
TBD is known as a superbase due to the high pKa of its conjugate acid [29,30]. Many unique reactions have been reported using TBD as an organocatalyst, such as the Henry reaction [31], Wittig and Horner-Wadsworth-Emmons reaction [32], Michael reaction [33], ring-opening polymerization [34], conjugate addition to activated alkenes [35], aminolysis of esters [36,37], intramolecular aldol reaction [38], and synthesis of pyrazolines [39], etc. [40,41,42,43]. Mechanistic studies of these reactions also have been discussed [44,45,46,47]. In some cases, it is considered that TBD acts as an acid-base bifunctional catalyst. Recently, we have also reported the trifluoromethylataion of aldehydes [48], and the ring-opening of aziridines with TMSCN [49] catalyzed by TBD as an organocatalyst. Herein, we report that TBD acts as an effective organobase catalyst for the ring-opening reaction of aziridines with acid anhydride.

2. Results and Discussion

Initially, the ring-opening reaction of N-tosylaziridine 1a with acetic anhydride was examined. The reaction was carried out by adding the 1a and acetic anhydride in the presence of 5 mol % of TBD in DMF at 50 °C. The reaction was monitored by TLC. Hydrolytic work up with saturated NH4Cl at room temperature followed by flash column chromatography afforded the ring-opened products. The product was obtained at 78% yield in 24 h along with 18% of the starting material. Although the reaction was performed for 48 h, the starting material did not disappear. Then the reaction was examined at elevated temperature (80 °C), and the reaction proceeded smoothly. The desired product was obtained at 94% yield in 4 h (Table 1, entry 2). This reaction also proceeded smoothly when 2 mol % of TBD was used (Table 1, entry 3). Among the screened solvents, DMF has proved to be the most effective for this reaction (Table 1, entries 1 vs. 4–6). The product was obtained in lower yield when other bases, such as DBU, TMG, TTMPP and DMAP (Figure 1) were used instead of TBD (Table 1, entries 1 vs. 7–10). An approximately comparable yield was observed when MTBD was used as a catalyst (Table 1, entry 11).
Molecules 20 18482 g001 550
Figure 1. Various bases.
Figure 1. Various bases.
Molecules 20 18482 g001
Table
Table 1. Optimization of the reaction conditions. Molecules 20 18482 i001
Table 1. Optimization of the reaction conditions. Molecules 20 18482 i001
EntryCatalystSolventYield (%)
1TBDDMF a,b78
2 DMF94
3 DMF c90
4 THF b,d45
5 MeCN b,e10
6 toluene b71
7DBUDMF b55
8TMGDMF b33
9DMAPDMF b34
10TTMPPDMF61
11MTBDDMF b80
a at room temperature. b in 24 h. c 2 mol % of TBD was used. d at 66 °C (reflux condition). e at 82 °C (reflux condition).
To clarify the scope of this reaction, several N-tosylaziridines and acid anhydrides were examined in the presence of 5 mol % TBD. In all cases, reactions were very clean and the desired products were afforded in good to excellent yields. Almost complete regioselectivity was observed when using alkyl-N-tosyl aziridines as substrates, and reaction on the less-substituted aziridine carbon was observed (Table 2, entries 7–10). For aryl-N-tosyl aziridines, in the case of a Lewis acid catalyzed reaction, selectivity demonstrated an opposite trend with alkyl-N-tosyl aziridines due to an electronic effect. Thus, the attack of the nucleophile at the benzylic position of aziridine occurred. However, in this Lewis base catalyzed reaction, the selectivity demonstrated the same trend: the reaction occurred on the less-substituted aziridine carbon (Table 2, entries 11–14). Reaction of propionic anhydride and benzoic anhydride also proceeded smoothly to afford the corresponding β-amino acetals in high yield. When propionic anhydride was used, regioselectivity was slightly higher than the reaction using acetic anhydride. In addition, cycloalkyl-N-tosyl aziridines also worked well. Unfortunately, no reaction occurred when non-acitivated aziridine such as N-benzylcyclohexylaziridine was employed.
Furthermore, we applied a polymer-supported TBD, PS-TBD [50,51,52,53] to this reaction. Polymer-supported catalysts have attracted significant attention in recent decades due to their inherent advantages in synthetic chemistry, e.g., simplification of reaction procedures including easy recovery of the catalyst by filtration, application to automated systems, and recycling of the catalyst [54,55,56,57,58,59]. Some unique reactions have been reported using TBD as an organocatalyst [31,60,61,62,63,64,65]. Thus, we examined the ring-opening reaction of N-tosylaziridine 1a with acetic anhydride in the presence of 10 mol % of PS-TBD. As shown in Table 3, the reaction proceeded smoothly and the desired product was obtained at 85% yield in 10 h at 80 °C in DMF. A variety of N-tosylaziridines reacted well with acetic anhydrides to give β-amino acetates. The reaction also occurred on the less substituted aziridine carbon regardless of the type of aziridine. In addition, the recovery and reuse of PS-TBD for the reaction of N-tosylaziridine 1a with acetic anhydrides also examined. After the reaction was completed, ethyl acetate was added to the reaction mixture and the catalyst was recovered by filtration. The recovered catalyst was washed, dried and then reused. The catalyst was reused, maintaining its catalytic activity after 4 uses (Table 3, entries 1–4).
Table
Table 2. TBD catalyzed ring-opening of various aziridines with acid anhydrides. Molecules 20 18482 i002
Table 2. TBD catalyzed ring-opening of various aziridines with acid anhydrides. Molecules 20 18482 i002
EntryAziridineRTimeProductYield (%) a
1 Molecules 20 18482 i003CH34 h Molecules 20 18482 i00494
2C2H54 h Molecules 20 18482 i00589
3C6H58 h Molecules 20 18482 i00691
4 b Molecules 20 18482 i007CH312 h Molecules 20 18482 i00885
5C2H518 h Molecules 20 18482 i00983
6 Molecules 20 18482 i010CH34 h Molecules 20 18482 i01186
7C2H56 h Molecules 20 18482 i01287
8C6H512 h Molecules 20 18482 i01388
9 Molecules 20 18482 i014CH34 h Molecules 20 18482 i01592
10C2H58 h Molecules 20 18482 i01698
11 Molecules 20 18482 i017CH31 h Molecules 20 18482 i01897 b
12C2H54 h Molecules 20 18482 i01995 c
13 Molecules 20 18482 i020CH31 h Molecules 20 18482 i02198 d
14C2H54 h Molecules 20 18482 i02296 e
a Isolated yield. b Regioisomer ratio 2e:3e = 85:15. c Regioisomer ratio 2eʹ:3eʹ = 94:6. d Regioisomer ratio 2f:3f = 87:13. e Regioisomer ratio 2fʹ: 3fʹ = 90:10.
Table
Table 3. PS-TBD catalyzed ring-opening of various aziridines with acetic anhydride. Molecules 20 18482 i023
Table 3. PS-TBD catalyzed ring-opening of various aziridines with acetic anhydride. Molecules 20 18482 i023
EntryAziridineProductTimeYield (%) a
1 Molecules 20 18482 i024 Molecules 20 18482 i02510 h85
210 h88 b
310 h80 c
410 h82 d
5 Molecules 20 18482 i026 Molecules 20 18482 i02724 h89
6 Molecules 20 18482 i028 Molecules 20 18482 i02916 h78
7 Molecules 20 18482 i030 Molecules 20 18482 i0314 h92
8 Molecules 20 18482 i032 Molecules 20 18482 i0338 h86
9 Molecules 20 18482 i034 Molecules 20 18482 i0358 h80
a Isolated yield. b 2nd run. c 3rd run. d 4th run.
A possible mechanism is illustrated in Scheme 1. First, TBD activated the anhydride to form N+C(O)R, RC(O)O− intermediate A. Next, this intermediate immediately reacts with aziridines to give the ring-opening product B. Finally, acylation occurs to give the N-acylated adduct with regeneration of TBD.
In this transition state, a steric effect has greater priority over the electronic effect (Scheme 2). Therefore, in this Lewis base catalyzed reaction, selectivity is not dependent on a substituent. The reaction occurred on the less-substituted aziridine carbon even in the case of phenyl substituted aziridine 1e.
Molecules 20 18482 g002 550
Scheme 1. Proposed mechanism.
Scheme 1. Proposed mechanism.
Molecules 20 18482 g002
Molecules 20 18482 g003 550
Scheme 2. The origin of regioselectivity.
Scheme 2. The origin of regioselectivity.
Molecules 20 18482 g003

3. Experimental Section

3.1. General

All reactions were performed under an argon atmosphere using oven-dried glassware. Flash column chromatography was performed using silica gel Wakogel C-200 (Wako Chemical, Osaka, Japan). Preparative thin-layer chromatography was carried out on silica gel Wakogel B-5F (Wako Chemical). Dehydrate DMF, THF, toluene and CH3CN were purchased from Wako Chemical. Other commercially available reagent was used as received without further purification. The aziridines were prepared according to literature procedure [66]. Yields refer to isolated compounds estimated to be >95% pure, as determined by 1H-NMR spectroscopy. IR spectra were recorded on a JUSCO FT/IR-430 spectrometer (JASCO Corporation, Tokyo, Japan). 1H- and 13C-NMR spectra were determined for solutions in CDCl3 with Me4Si as internal standard on a Bruker Avance III instrument (Bruker Corporation, Billerica, MA, USA). HRMS data were measured on a JEOL JMS-700 mass spectrometer (JEOL Ltd., Tokyo, Japan).

3.2. Method

3.2.1. General Procedure for TBD-Catalyzed Ring-Opening of Aziridines with Acid Anhydride

To a solution of TBD (0.05 mmol) in DMF (1 mL) was added aziridine (1.0 mmol) and acid anhydride (1.25 mmol) at room temperature. After the reaction was complete (as determinedby TLC), the reaction mixture was washed with saturated NH4Cl and extracted with EtOAc (2 × 10 mL). The combined organic layers were dried over Na2SO4, concentrated in vacuo and purified by column chromatography on silica gel (EtOAc:hexane = 1:3) to give the corresponding product.

3.2.2. General Procedure for PS-TBD Catalyzed Ring-Opening of Aziridines with Acid Anhydride

To a solution of PS-TBD (0.10 mmol) in DMF (1 mL) was added aziridine (1.0 mmol) and acid anhydride (1.25 mmol) at room temperature. After the reaction was complete (as determined by TLC), EtOAc (5 mL) was added to the mixture and PS-TBD was separated by filtration. The filtrate was washed with saturated NH4Cl, dried over Na2SO4. The organic layer was concentrated in vacuo and purified by column chromatography on silica gel (EtOAc:hexane = 1:3) to give the corresponding product. The recovered catalyst is reusable after washing (acetone and water) and drying in vacuo.

3.3. General Characterization of the Products

2-(4-Methylphenylsulfonamido)cyclohexyl acetate (2a) [23]. Colorless plate; m.p. 108–110 °C; yield: 294 mg (94%); IR (KBr): 3030, 2929, 2195, 1644, 1598, 1449, 823, 700 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.16–1.32 (m, 4H), 1.57–1.61 (m, 1H), 1.62–1.66 (m, 1H), 1.74 (s, 3H), 1.85–1.89 (m, 1H), 1.96–2.00 (m, 1H), 2.38 (s, 3H), 3.12–3.18 (m, 1H), 4.53 (dt, J = 4.6, 10.4 Hz, 1H), 4.95 (d, J = 6.8 Hz, 1H), 7.25 (d, J = 8.0 Hz, 2H), 7.71 (d, J = 8.0 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 20.9, 21.5, 23.6, 24.2, 31.1, 33.5, 56.9, 74.1, 126.9, 129.6, 138.7, 143.0, 171.4; HRMS (FAB): m/z: cald for C15H22NO4S: 312.1270; found: 312.1280 [M + H]+.
2-(4-Methylphenylsulfonamido)cyclohexyl propionate (2aʹ) [23]. Colorless cube; m.p. 92–94 °C; yield: 289 mg (89%); IR (KBr): 3284, 2957, 1736, 1460, 1331, 1162, 1092, 815, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.02 (t, J = 7.5 Hz, 3H), 1.20–1.39 (m, 4H), 1.62–1.67 (m, 1H), 1.68–1.71 (m, 1H), 1.95–1.99 (m, 1H), 2.00–2.05 (m, 1H), 2.07 (q, J = 7.5 Hz, 2H), 2.42 (s, 3H), 3.19-3.24 (m, 1H), 4.59 (dq, J = 3.4, 10.4 Hz, 1H), 5.04 (d, J = 10.4 Hz, 1H), 7.29 (d, J = 8.6 Hz, 2H), 7.74 (d, J = 8.6 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.8, 21.4, 23.6, 24.1, 27.4, 31.0, 33.3, 56.9, 73.8, 126.8, 129.5, 138.7, 142.9, 174.8; HRMS (FAB): m/z: cald for C16H24NO4S: 326.1426; found: 326.1410 [M + H]+.
2-(4-Methylphenylsulfonamido)-1-phenylcarbonyloxyclohexane (2aʹʹ) [24]. White solid; m.p. 128–130 °C; yield: 340 mg (91%); IR (KBr): 3321, 2926, 1786, 1702, 1598, 1450, 1320, 1212, 1155, 1014, 715, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.20–1.28 (m, 2H), 1.27–1.42 (m, 2H), 1.64–1.66 (m, 1H), 1.67–1.71 (m, 1H), 1.95–2.01 (m, 1H), 2.10–2.17 (m, 1H), 2.15 (s, 3H), 3.26–3.32 (m, 1H), 4.79 (dt, J = 4.7, 10.7 Hz, 1H), 5.16 (d, J = 7.4 Hz, 1H), 6.88 (d, J = 8.0 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 7.50 (d, J = 6.4 Hz, 1H), 7.55 (d, J = 8.2 Hz, 2H), 7.74 (d, J = 7.0 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 21.2, 23.6, 24.1, 31.1, 33.8, 57.1, 74.5, 126.4, 128.0, 128.8, 129.3, 129.6, 130.4, 132.8, 138.0, 142.5, 166.6; HRMS (FAB): m/z: cald for C20H24NO4S: 374.1426; found: 374.1420 [M + H]+.
2-(4-Methylphenylsulfonamido)cyclopentyl acetate (2b) [23]. Colorless oil; yield: 253 mg (85%); IR (neat): 3278, 2925, 1732, 1455, 1326, 1158, 1092, 815, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.44–1.50 (m, 2H), 1.57–1.64 (m, 2H), 1.84 (s, 3H), 1.95–1.99 (m, 2H), 2.39 (s, 3H), 3.40–3.44 (m, 1H), 4.82 (dt, J = 5.5, 7.5 Hz, 1H), 5.33–5.39 (brs, 1H), 7.26 (d, J = 8.1 Hz, 2H), 7.72 (d, J = 8.1 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 20.7, 20.8, 21.4, 29.3, 31.0, 59.7, 79.5, 127.1, 129.5, 137.3, 143.3, 171.0; HRMS (FAB): m/z: cald for C14H20NO4S: 298.1113; found: 298.1118 [M + H]+.
2-(4-Methylphenylsulfonamido)cyclopentyl propionate (2bʹ) [25]. Colorless oil; yield: 258 mg (83%); IR (neat): 3276, 2941, 1741, 1462, 1356, 1165, 813, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 0.94 (t, J = 7.6 Hz, 3H), 1.40–1.45 (m, 2H), 1.50–1.57 (m, 2H), 1.85–1.95 (m, 2H), 2.00–2.10 (m, 2H), 2.32 (s, 3H), 3.33–3.40 (m, 1H), 4.80 (dt, J = 5.4, 7.4 Hz, 1H), 5.70 (d, J = 7.4 Hz, 1H), 7.21 (d, J = 8.1 Hz, 2H), 7.68 (d, J = 8.1 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.7, 20.6, 27.2, 29.2, 30.8, 59.4, 79.2, 126.9, 129.3, 137.3, 143.1, 174.2; HRMS (FAB): m/z: cald for C15H22NO4S: 312.1270; found: 312.1285 [M + H]+.
2-(4-Methylphenylsulfonamido)hexyl acetate (2c) [23]. Colorless oil; yield: 269 mg (86%); IR (neat): 3281, 2957, 2871, 1741, 1598, 1431, 1329, 1239, 1162, 1093, 815, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 0.76 (t, J = 7.2 Hz, 3H), 1.06–1.30 (m, 4H), 1.32–1.45 (m, 2H), 1.90 (s, 3H), 2.39 (s, 3H), 3.38–3.43 (m, 1H), 3.85 (dd, J = 4.3, 11.4 Hz, 1H), 3.94 (dd, J = 5.4, 11.4 Hz, 1H), 4.90 (d, J = 8.5 Hz, 1H), 7.26 (d, J = 7.9 Hz, 2H), 7.73 (d, J = 7.9 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 13.7, 20.6, 21.4, 22.2, 27.4, 32.0, 52.8, 65.7, 127.0, 129.6, 138.1, 143.3, 170.8; HRMS (FAB): m/z: cald for C15H24NO4S: 314.1426; found: 314.1409 [M + H]+.
2-(4-Methylphenylsulfonamido)hexyl propionate (2cʹ) [26]. Colorless oil; yield: 285 mg (87%); IR (neat): 3283, 2957, 1740, 1462, 1330, 1162, 1092, 815, 667 cm−1; 1H-NMR (500 Hz, CDCl3) δ 0.76 (t, J = 7.1 Hz, 3H), 1.05 (t, J = 7.6 Hz, 3H), 1.15–1.25 (m, 4H), 1.35–1.48 (m, 2H), 2.18 (q, J = 7.6 Hz, 2H), 2.39 (s, 3H), 3.36-3.45 (m, 1H), 3.86 (dd, J = 4.3, 11.4 Hz, 1H), 3.96 (dd, J = 5.5, 11.4 Hz, 1H), 4.77–4.82 (m, 1H), 7.26 (d, J = 8.4 Hz, 2H), 7.73 (d, J = 8.4 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.9, 13.7, 21.4, 22.2, 27.1, 27.4, 32.0, 52.9, 65.6, 126.9, 129.6, 138.1, 143.3, 174.2; HRMS (FAB): m/z: cald for C16H26NO4S: 328.1583; found: 328.1596 [M + H]+.
2-(4-Methylphenylsulfonamido)-1-phenylcarbonyloxyhexane (2cʹʹ) [23]. White solid; m.p. 65–69 °C; yield: 330 mg (88%); IR (KBr): 3288, 2929, 1787, 1560, 1452, 1273, 1162, 815, 708, 615 cm−1; 1H-NMR (500 Hz, CDCl3) δ 0.78 (t, J = 7.2 Hz, 3H), 1.13–1.31 (m, 4H), 1.45–1.59 (m, 2H), 2.29 (s, 3H), 3.53–3.62 (m, 1H), 4.11 (dd, J = 4.2, 11.5 Hz, 1H), 4.22 (dd, J = 5.6, 11.5 Hz, 1H), 5.16 (d, J = 8.3 Hz, 1H), 7.11 (d, J = 8.0 Hz, 2H), 7.36 (t, J = 7.5 Hz, 2H), 7.52 (t, J = 7.5 Hz, 1H), 7.71 (d, J = 8.3 Hz, 2H), 7.89 (d, J = 7.1 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 13.7, 21.4, 22.2, 27.5, 32.2, 53.0, 66.2, 126.8, 128.2, 129.6, 133.1, 138.0, 143.2, 166.2; HRMS (FAB): m/z: cald for C20H26NO4S: 376.1583; found: 374.1564 [M + H]+.
2-(4-Methylphenylsulfonamido)-3-phenylpropyl acetate (2d) [23]. White solid; m.p. 67–69 °C; yield: 320 mg (92%); IR (KBr): 3280, 2953, 1742, 1455, 1329, 1160, 1092, 815, 667 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.93 (s, 3H), 2.37 (s, 3H), 2.75 (d, J = 7.0 Hz, 2H), 3.62–3.69 (m, 1H), 3.90 (dd, J = 5.3, 15.0 Hz, 1H), 3.92 (dd, J = 5.4, 15.0 Hz, 1H), 5.18 (d, J = 8.1 Hz, 1H), 7.00 (d, J = 8.0 Hz, 2H), 7.14–7.22 (m, 5H), 7.62 (d, J = 8.2 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 20.6, 21.3, 38.5, 53.8, 64.8, 126.7, 126.8, 128.6, 129.1, 129.5, 136.2, 137.5, 143.2, 170.7; HRMS (FAB): m/z: cald for C18H22NO4S: 348.1270; found: 348.1254 [M + H]+.
2-(4-Methylphenylsulfonamido)-3-phenylpropyl propionate (2dʹ) [25]. Colorless oil; yield: 354 mg (98%); IR (neat): 3281, 2942, 1740, 1456, 1330, 1160, 1092, 814, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.08 (t, J = 7.6 Hz, 3H), 2.20 (q, J = 7.6 Hz, 2H), 2.40 (s, 3H), 3.34-3.41 (m, 1H), 3.92 (dd, J = 4.7, 11.5 Hz, 1H), 3.97 (dd, J = 5.5, 11.5 Hz, 1H), 4.84 (d, J = 7.9 Hz, 1H), 7.02 (d, J = 7.3Hz, 2H), 7.16–7.23 (m, 5H), 7.63 (d, J = 8.3 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.9, 21.4, 27.2, 38.5, 53.9, 64.7, 126.8, 126.9, 128.7, 129.2, 129.6, 136.2, 137.6, 143.3, 174.1; HRMS (FAB): m/z: cald for C19H24NO4S: 362.1426; found: 362.1445 [M + H]+.
2-(4-Methylphenylsulfonamido)-2-phenylethyl acetate (2e) [23]. Colorless oil; yield: 300 mg (90%); IR (neat): 3280, 2923, 1742, 1434, 1328, 1160, 1092, 814, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.91 (s, 3H), 2.35 (s, 3H), 4.14 (dd, J = 4.9, 11.6 Hz, 1H), 4.18 (dd, J = 7.9, 11.6 Hz, 1H), 4.60 (dt, J = 4.9, 7.3 Hz, 1H), 5.43 (d, J = 7.0 Hz, 1H), 7.08–7.12 (m, 4H), 7.16–7.18 (m, 2H), 7.26–7.30 (m, 1H), 7.57 (d, J = 8.4 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 20.6, 21.3, 56.9, 66.5, 126.8, 127.1, 128.6, 129.4, 137.0, 137.5, 143.3, 170.8; HRMS (FAB): m/z: cald for C17H20NO4S: 334.1113; found: 334.1119 [M + H]+.
2-(4-Methylphenylsulfonamido)-2-phenylethyl propionate (2eʹ) [25]. Colorless oil; yield: 306 mg (88%); IR (neat): 3280, 2924, 1741, 1516, 1438, 1160, 1090, 813, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.02 (t, J = 7.6 Hz, 3H), 2.18 (q, J = 7.6 Hz, 2H), 2.35 (s, 3H), 4.17 (dd, J =5.0 Hz, 11.6 Hz, 1H), 4.20 (dd, J = 7.4, 11.6 Hz, 1H), 4.62 (dt, J = 4.9, 7.3 Hz, 1H), 5.72 (d, 6.6 Hz, 1H), 7.12–7.15 (m, 4H), 7.17–7.19 (m, 2H), 7.27–7.30 (m, 1H), 7.59 (d, J = 8.3 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.8, 21.3, 27.1, 56.9, 66.3, 126.8, 127.0, 128.5, 129.3, 137.1, 137.4, 143.1, 174.2; HRMS (FAB): m/z: cald for C18H22NO4S: 348.1270; found: 348.1262 [M + H]+.
2-(4-Methylphenylsulfonamido)-2-(4-methylphenyl)ethyl acetate (2f) [23]. White solid; m.p. 88–90 °C; yield: 316 mg (91%); IR (neat): 3278, 2925, 1742, 1495, 1330, 1161, 1044, 815, 668 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.93 (s, 3H), 2.28 (s, 3H), 2.38 (s, 3H), 4.14 (dd, J = 4.8, 11.6 Hz, 1H), 4.19 (dd, J = 7.6, 11.6 Hz, 1H), 4.56 (dt, J = 4.9, 7.3 Hz, 1H), 5.66 (dd, J = 5.0, 7.3 Hz, 1H), 7.00–7.02 (m, 4H), 7.17 (d, J = 8.0 Hz, 2H), 7.60 (d, J = 8.0 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 20.6, 21.0, 21.4, 56.5, 66.4, 126.7, 127.0, 129.2, 129.3, 133.9, 137.4, 137.8, 143.2, 170.8; HRMS (FAB): m/z: cald for C18H22NO4S: 348.1270; found: 348.1288 [M + H]+.
2-(4-Methylphenylsulfonamido)-2-(4-methylphenyl)ethyl acetate (2fʹ) [25]. White solid; m.p. 98–100 °C; yield: 310 mg (83%); IR (neat): 3283, 2982, 1740, 1598, 1462, 1348, 1161, 1088, 814, 666 cm−1; 1H-NMR (500 Hz, CDCl3) δ 1.04 (t, J = 7.6 Hz, 3H), 2.20 (q, J = 7.6 Hz, 2H), 2.28 (s, 3H), 2.38 (s, 3H), 4.15 (dd, J =4.8, 11.6 Hz, 1H), 4.20 (dd, J = 7.6, 11.6 Hz, 1H), 4.57 (dt, J = 4.8, 7.2 Hz, 1H), 5.22 (d, J = 6.8 Hz, 1H), 7.00–7.02 (m, 4H), 7.17 (d, J = 8.0 Hz, 2H), 7.59 (d, J = 8.0 Hz, 2H); 13C-NMR (125 MHz, CDCl3) δ 8.8, 21.0, 21.4, 56.7, 66.3, 126.7, 127.0, 129.2, 129.4, 134.0, 137.4, 137.9, 143.2, 174.3; HRMS (FAB): m/z: cald for C19H24NO4S: 362.1426; found: 362.1415 [M + H]+.
Copies of 1H- and 13C-NMR Spectra of products 2a–2f, 2aʹ–2fʹ, 2aʹʹ, and 2cʹʹ could be found in the supplementary materials.

4. Conclusions

In conclusion, we have demonstrated TBD catalyzed ring-opening reactions of N-tosylaziridine with acid anhydrides. A broad range of N-tosylaziridine and acid anhydrides could be applied using 5 mol % TBD. Furthermore, polymer-supported catalyst, PS-TBD also act as a good catalyst for this reaction. PS-TBD was easily recovered and reused with minimal loss of activity. These reactions provide a simple and convenient method for the synthesis of highly functionalized β-amino alcohols.

Supplementary Materials

Supplementary materials can be accessed at: https://www.mdpi.com/1420-3049/20/10/18482/s1.

Author Contributions

S.M. conceived the ideas, analyzed the data, and wrote the paper; Y.M. performed the experiments, analyzed the data; All authors read and approved the final manuscript.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Sweeney, J.B. Aziridines: Epoxides’ ugly cousins? Chem. Soc. Rev. 2002, 31, 247–258. [Google Scholar] [CrossRef] [PubMed]
  2. Padwa, A.; Pearson, W.H.; Lian, B.N.; Bergmeier, S.C. Comprehensive Heterocyclic Chemistry II; Katritzky, A.R., Rees, C.W., Scriven, E.F.V., Eds.; Pergamon: New York, NY, USA, 1996; Volume 1a, pp. 1–96. [Google Scholar]
  3. Tanner, D. Chiral Aziridines—Their Synthesis and Use in Stereoselective Transformations. Angew. Chem. Int. Ed. Engl. 1994, 33, 599–619. [Google Scholar] [CrossRef]
  4. Hu, X.E. Nucleophilic ring opening of aziridines. Tetrahedron 2004, 60, 2701–2743. [Google Scholar] [CrossRef]
  5. Watson, I.D.G.; Yu, L.; Yudin, A.K. Advances in nitrogen transfer reactions involving aziridines. Acc. Chem. Res. 2006, 39, 194–206. [Google Scholar] [CrossRef] [PubMed]
  6. Singh, G.S.; D’hooghe, M.; Kimpe, N.D. Aziridines synthesis and reactivity of C-heteroatom-substituted aziridines. Chem. Rev. 2007, 107, 2080–2135. [Google Scholar] [CrossRef] [PubMed]
  7. Lu, P. Recent developments in regioselective ring opening of aziridines. Tetrahedron 2010, 66, 2549–2560. [Google Scholar] [CrossRef]
  8. Chawla, R.; Singh, A.K.; Yadav, L.D.S. Organocatalysis in synthesis and reactions of epoxides and aziridines. RSC Adv. 2013, 3, 11385–11403. [Google Scholar] [CrossRef]
  9. Llaveria, J.; Beltran, A.; Díaz-Requejo, M.M.; Matheu, M.I.; Castillon, S.; Perez, P.J. Efficient Silver-Catalyzed Regio- and Stereospecific Aziridination of Dienes. Angew. Chem. Int. Ed. 2010, 49, 7092–7095. [Google Scholar] [CrossRef] [PubMed]
  10. Llaveria, J.; Beltran, A.; Sameera, W.M.C.; Locati, A.; Diaz-Requejo, M.M.; Matheu, M.I.; Castillon, S.; Maseras, F.; Perez, P.J. Chemo-, Regio-, and Stereoselective Silver-Catalyzed Aziridination of Dienes: Scope, Mechanistic Studies, and Ring-Opening Reactions. J. Am. Chem. Soc. 2014, 136, 5342–5350. [Google Scholar] [CrossRef] [PubMed]
  11. Davis, F.A.; Zhou, P. Asymmetric synthesis of the antibiotic (+)-thiamphenicol using cis-N-(p-toluenesulfinyl)aziridine 2-carboxylic acids. Tetrahedron 1994, 35, 7525–7528. [Google Scholar] [CrossRef]
  12. Davis, F.A.; Reddy, G.V. Aziridine-2-carboxylic acid mediated asymmetric synthesis of d-erythro- and l-threo-sphingosine from a common precursor. Tetrahedron Lett. 1996, 37, 4349–4352. [Google Scholar] [CrossRef]
  13. Cardillo, G.; Gentilucci, L.; Tolomelli, A.; Tomasini, C. Ring expansion of N-acyl aziridine-2-imides to oxazoline-4-imides, useful precursors of pure beta-hydroxy alpha-aminoacids. Tetrahedron Lett. 1997, 39, 6953–6956. [Google Scholar] [CrossRef]
  14. Prasad, P.A.B.; Sekar, G.V.; Singh, K. An efficient method for the cleavage of aziridines using hydroxyl compound. Tetrahedron Lett. 2000, 41, 4677–4679. [Google Scholar] [CrossRef]
  15. Olofsson, B.; Khamrai, U.; Somfai, P. A regio- and stereodivergent synthesis of vic-amino alcohols. Org. Lett. 2000, 2, 4087–4089. [Google Scholar] [CrossRef] [PubMed]
  16. Saha, B.; Nandy, J.P.; Shukla, S.; Siddiqui, I.; Iqbal, J. Stereoselective synthesis of beta-substituted phenylalanine-beta-phenylisoserine-derived tripeptides using N-cinnamoyl-l-proline as template: Synthesis of structural analogues of HIV protease inhibitors. J. Org. Chem. 2002, 67, 7858–7860. [Google Scholar] [CrossRef] [PubMed]
  17. Prasad, P.A.B.; Sanghi, R.; Singh, K. Studies on ring cleavage of aziridines with hydroxyl compound. Tetrahedron 2002, 58, 7355–7363. [Google Scholar] [CrossRef]
  18. Olofsson, B.; Somfai, P. A regio- and stereodivergent route to all isomers of vic-amino alcohols. J. Org. Chem. 2002, 67, 8574–8583. [Google Scholar] [CrossRef] [PubMed]
  19. Chakraborty, T.K.; Ghosh, A.; Raju, T.V. Efficient ring opening reactions of N-tosyl aziridines with amines and water in presence of catalytic amount of cerium(IV) ammonium nitrate. Chem. Lett. 2003, 32, 82–83. [Google Scholar] [CrossRef]
  20. Concellon, J.M.; Riego, E. Ring opening of nonactivated 2-(1-aminoalkyl) aziridines: Unusual regio- and stereoselective C-2 and C-3 cleavage. J. Org. Chem. 2003, 68, 6407–6410. [Google Scholar] [CrossRef] [PubMed]
  21. Wang, Z.; Cui, Y.T.; Xu, Z.B.; Qu, J. Hot water-promoted ring-opening of epoxides and aziridines by water and other nucleopliles. J. Org. Chem. 2008, 73, 2270–2274. [Google Scholar] [CrossRef] [PubMed]
  22. Li, X.; Ni, B.; Chang, H.-H.; Wei, W.-L. NaHSO3-promoted ring openings of N-tosylaziridines and epoxides with H2O. Heterocycles 2014, 89, 1009–1016. [Google Scholar]
  23. Yadav, J.S.; Reddy, B.V.; Sadashiv, K.; Harikishan, K. Indium triflate-catalyzed ring opening of aziridines with carboxylic acid. Tetrahedron Lett. 2002, 43, 2099–2101. [Google Scholar] [CrossRef]
  24. Fan, R.-H.; Hou, X.-L. Tributylphosphine-catalyzed ring-opening reaction of epoxides and aziridines with acetic anhydride. Tetrahedron Lett. 2003, 44, 4411–4413. [Google Scholar] [CrossRef]
  25. Yadav, J.S.; Reddy, B.V.S.; Sadashiv, K.; Harikishan, K.; Narsaiah, A.V. Acylative cleavage of aziridines with acid anhydrides catalyzed by Scandium triflate. J. Mol. Catal. A 2004, 220, 153–157. [Google Scholar] [CrossRef]
  26. Das, B.; Reddy, V.S.; Tehseen, F. A mild, rapid and highly regioselective ring-opening of epoxides and aziridines with acetic anhydride under solvent-free conditions using ammonium-12-molybdophosphate. Tetrahedron Lett. 2006, 47, 6865–6868. [Google Scholar] [CrossRef]
  27. Sun, X.; Ye, S.; Wu, J. N-Heterocyclic Carbene: An efficient catalyst for the ring-opening reaction of aziridine with acid anhydride. Eur. J. Org. Chem. 2006, 4787–4790. [Google Scholar] [CrossRef]
  28. Li, X.; Li, G.; Chang, H.; Zhang, Y.; Wei, W. Tetrabutylammonium bromide-mediated ring opening reactions of N-tosylaziridines with carboxylic acids in DMF. RSC Adv. 2014, 4, 6490–6495. [Google Scholar] [CrossRef]
  29. Schroeder, G.; Łeska, B.; Jarczewski, A.; Nowak-Wydra, B.; Brzezinski, B. FTIR, NMR and kinetic studies of proton transfer reactions from nitro-substituted diarylmethanes to N-bases with guanidine character. J. Mol. Struct. 1995, 344, 77–88. [Google Scholar] [CrossRef]
  30. Coles, M.P. Bicyclic-guanidines, -guanidinates and -guanidinium salts: Wide ranging applications from a simple family of molecules. Chem. Commun. 2009, 3659–3676. [Google Scholar] [CrossRef] [PubMed]
  31. Simoni, D.; Rondanin, R.; Morini, M.; Baruchello, R.; Invidata, F.P. 1,5,7-Triazabicyclo [4.4.0]dec-1-ene (TBD), 7-methyl-TBD (MTBD) and the polymer-supported TBD (P-TBD): Three efficient catalysts for the nitroaldol (Henry) reaction and for the addition of dialkyl phosphites to unsaturated systems. Tetrahedron Lett. 2000, 41, 1607–1610. [Google Scholar] [CrossRef]
  32. Simoni, D.; Rossi, M.; Rondanin, R.; Mazzali, A.; Baruchello, R.; Malagutti, C.; Roberti, M.; Invidata, F.P. Strong bicyclic guanidine base-promoted Wittig and Horner-Wadsworth-Emmons reactions. Org. Lett. 2000, 2, 3765–3768. [Google Scholar] [CrossRef] [PubMed]
  33. Ye, W.; Xu, J.; Tan, C.-T.; Tan, C.-H. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) catalyzed Michael reactions. Tetrahedron Lett. 2005, 46, 6875–6878. [Google Scholar] [CrossRef]
  34. Pratt, R.C.; Lohmeijer, B.G.G.; Long, D.A.; Waymouth, R.A.; Hedric, J.A. Triazabicyclodecene: A simple bifunctional organocatalyst for acyl transfer and ring-opening polymerization of cyclic esters. J. Am. Chem. Soc. 2006, 129, 4556–4557. [Google Scholar] [CrossRef] [PubMed]
  35. Jiang, Z.; Zhang, Y.; Ye, W.; Tan, C.-H. P–C Bond formation via direct and three-component conjugate addition catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Tetrahedron Lett. 2007, 48, 51–54. [Google Scholar] [CrossRef]
  36. Sabot, C.; Kumar, K.A.; Meunier, S.; Mioskowski, C. A convenient aminolysis of esters catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) under solvent-free conditions. Tetrahedron Lett. 2007, 48, 3863–3866. [Google Scholar] [CrossRef]
  37. Sabot, C.; Kumar, K.A.; Antheaume, C.; Mioskowski, C. Triazabicyclodecene: An Effective Isotope Exchange Catalyst in CDCl3. J. Org. Chem. 2007, 72, 5001–5004. [Google Scholar] [CrossRef] [PubMed]
  38. Ghobril, C.; Sabot, C.; Mioskowski, C.; Baati, R. TBD-Catalyzed Direct 5- and 6-enolexo Aldolization of Ketoaldehydes. Eur. J. Org. Chem. 2008, 4104–4108. [Google Scholar] [CrossRef]
  39. Mahe, O.; Frath, D.; Dez, I.; Marsais, F.; Levacher, V.; Briere, J.-F. TBD-organocatalysed synthesis of pyrazolines. Org. Biomol. Chem. 2009, 7, 3648–3651. [Google Scholar] [CrossRef] [PubMed]
  40. Saliu, F.; Rindone, B. Organocatalyzed synthesis of ureas from amines and ethylene carbonate. Tetrahedron Lett. 2010, 51, 6301–6304. [Google Scholar] [CrossRef]
  41. Poladura, B.; Martínez-Castañeda, Á.; Rodríguez-Solla, H.; Concellón, C.; del Amo, V. TBD-catalyzed α-sulfenylation of cyclic ketones: Desymmetrization of 4-substituted cyclohexanone. Tetrahedron 2012, 68, 6438–6446. [Google Scholar] [CrossRef]
  42. Lanari, D.; Rosati, O.; Curini, M. A solvent-free protocol for the synthesis of 3-formyl-2H-chromenes via domino oxa Michael/aldol reaction. Tetrahedron Lett. 2014, 55, 1752–1755. [Google Scholar] [CrossRef]
  43. Deredas, D.; Huben, K.; Maniukiewicz, W.; Krawczyk, H. Highly syn-diastereoselective Michael addition of enolizable ketones to 3-(diethoxyphosphoryl)coumarin. Tetrahedron 2014, 70, 8925–8929. [Google Scholar] [CrossRef]
  44. Simón, L.; Goodman, J.M. The Mechanism of TBD-catalyzed ring-opening polymerization of cyclic esters. J. Org. Chem. 2007, 72, 9656–9662. [Google Scholar] [CrossRef] [PubMed]
  45. Kiesewetter, M.K.; Scholten, M.; Kirn, N.; Weber, R.L.; Hedrick, J.L.; Waymouth, R.M. Cyclic guanidine organic catalysts: What is magic about triazabicyclodecene? J. Org. Chem. 2009, 74, 9490–9496. [Google Scholar] [CrossRef] [PubMed]
  46. Hammar, P.; Ghobril, C.; Antheaume, C.; Wagner, A.; Baati, R.; Himo, F. Theoretical Mechanistic Study of the TBD-Catalyzed Intramolecular aldol reaction of ketoaldehydes. J. Org. Chem. 2010, 75, 4728–4736. [Google Scholar] [CrossRef] [PubMed]
  47. Fu, X.; Tan, C.-H. Mechanistic considerations of guanidine-catalyzed reactions. Chem. Commun. 2011, 47, 8210–8222. [Google Scholar] [CrossRef] [PubMed]
  48. Matsukawa, S.; Harada, T.; Takahashi, H. TBD-catalyzed ring opening of aziridines with silylated nucleophiles. Synth. Commun. 2013, 43, 406–414. [Google Scholar] [CrossRef]
  49. Matsukawa, S.; Takahashi, H.; Takahashi, S. TBD-catalyzed trifluoromethylation of carbonyl compounds with (trifluoromethyl)trimethylsilane. Synth Commun. 2013, 43, 1523–1529. [Google Scholar] [CrossRef]
  50. Tomoi, M.; Kato, Y.; Kakiuchi, H. Polymer-supported bases, 2. Polystyrene-supported 1,8-diazabicyclo[5.4.0]undec-7-ene as reagent in organic syntheses. Makromol. Chem. 1984, 185, 2117–2124. [Google Scholar] [CrossRef]
  51. Iijima, K.; Fukuda, W.; Tomoi, M. Polymer-supported bases. XI. Esterification and alkylation in the presence of polymer-supported bicyclic amidine or guanidine moieties. J. Macromol. Sci. A Pure Appl. Chem. 1992, 29, 249–261. [Google Scholar] [CrossRef]
  52. Xu, W.; Mohan, R.; Morrissey, M.M. Polymer supported bases in combinatorial chemistry: Synthesis of aryl ethers from phenols and alkyl halides and aryl halides. Tetrahedron. Lett. 1997, 38, 7337–7340. [Google Scholar] [CrossRef]
  53. Boisnard, S.; Chastanet, J.; Zhu, J. A high throughput synthesis of aryl triflate and aryl nonaflate promoted by a polymer supported base (PTBD). Tetrahedron Lett. 1999, 40, 7469–7472. [Google Scholar] [CrossRef]
  54. McNamara, C.A.; Dixon, M.J.; Bradley, M. Recoverable catalysts and reagents using recyclable polystyrene-based supports. Chem. Rev. 2002, 102, 3275–3300. [Google Scholar] [CrossRef] [PubMed]
  55. Benaglia, M.; Puglisi, A.; Cozzi, F. Polymer-supported organic catalysts. Chem. Rev. 2003, 103, 3401–3429. [Google Scholar] [CrossRef] [PubMed]
  56. Cozzi, F. Immobilization of organic catalysts: When, why, and how. Adv. Synth. Catal. 2006, 348, 1367–1390. [Google Scholar] [CrossRef]
  57. Ikegami, S.; Hamamoto, H. Novel recycling system for organic synthesis via designer polymer-gel catalysts. Chem. Rev. 2009, 109, 583–593. [Google Scholar] [CrossRef] [PubMed]
  58. Lu, J.; Toy, P.H. Organic polymer supports for synthesis and for reagent and catalyst immobilization. Chem. Rev. 2009, 109, 815–838. [Google Scholar] [CrossRef] [PubMed]
  59. Kristensen, T.E.; Hansen, T. Polymer-supported chiral organocatalysts: Synthetic strategies for the road towards affordable polymeric immobilization. Eur. J. Org. Chem. 2010, 17, 3179–3204. [Google Scholar] [CrossRef]
  60. Fringuelli, F.; Pizzo, F.; Vittoriani, C.; Vaccaro, L. Polystyryl-supported TBD as an efficient and reusable catalyst under solvent-free conditions. Chem. Commun. 2004, 2756–2757. [Google Scholar] [CrossRef] [PubMed]
  61. Fringuelli, F.; Pizzo, F.; Vittoriani, C.; Vaccaro, L. Polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene as an efficient and reusable catalyst for the thiolysis of 1,2-epoxides under solvent-free conditions. Eur. J. Org. Chem. 2006, 1231–1236. [Google Scholar] [CrossRef]
  62. Lanari, D.; Balini, R.; Palmieri, A.; Pizzo, F.; Vaccaro, L. Diastereoselective three-step route to o-(6-nitrocyclohex-3-en-1-yl)phenol and tetrahydro-6H-benzo[c]chromen-6-ol derivatives from salicylaldehydes. Eur. J. Org. Chem. 2011, 2874–2884. [Google Scholar] [CrossRef]
  63. Matsukawa, S.; Fujikawa, S. Polystyrene-supported TBD as an efficient and reusable organocatalyst for cyanosilylation of aldehydes, ketones, and imines. Tetrahedron Lett. 2012, 53, 1075–1077. [Google Scholar] [CrossRef]
  64. Matsukawa, S.; Harada, T.; Yasuda, S. Polystyrene-supported TBD catalyzed ring-opening of N-tosylaziridines with silylated nucleophiles. Org. Biomol. Chem. 2012, 10, 4886–4890. [Google Scholar] [CrossRef] [PubMed]
  65. Matsukawa, S.; Tsukamoto, K.; Harada, T.; Yasuda, S. An efficient method for opening N-tosyl aziridines with silylated nucleophiles using polystyrene-supported TBD as a reusable organocatalyst. Synthesis 2013, 45, 2959–2965. [Google Scholar] [CrossRef]
  66. Thakur, V.V.; Sudalai, A. N-Bromoamides as versatile catalysts for aziridination of olefins using chloramine-T. Tetrahedron Lett. 2003, 44, 989–992. [Google Scholar] [CrossRef]
  • Sample Availability: Samples of the compounds 2a–2f, 2aʹ–2fʹ, 2aʹʹ, 2cʹʹ are available from the authors.

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Matsukawa, S.; Mouri, Y. A Mild and Regioselective Ring-Opening of Aziridines with Acid Anhydride Using TBD or PS-TBD as a Catalyst. Molecules 2015, 20, 18482-18495. https://doi.org/10.3390/molecules201018482

AMA Style

Matsukawa S, Mouri Y. A Mild and Regioselective Ring-Opening of Aziridines with Acid Anhydride Using TBD or PS-TBD as a Catalyst. Molecules. 2015; 20(10):18482-18495. https://doi.org/10.3390/molecules201018482

Chicago/Turabian Style

Matsukawa, Satoru, and Yasutaka Mouri. 2015. "A Mild and Regioselective Ring-Opening of Aziridines with Acid Anhydride Using TBD or PS-TBD as a Catalyst" Molecules 20, no. 10: 18482-18495. https://doi.org/10.3390/molecules201018482

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