Next Article in Journal
A New Approach to 5-Functionalized 1,2-Dihydropyrimidin-2-ones/imines via Base-Induced Chloroform Elimination from 4-Trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones/imines
Previous Article in Journal
Expeditious Multicomponent Synthesis of Xanthone Dimers
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Proceedings
Volume 9
Issue 1
10.3390/ecsoc-22-05683
proceedings-logo
Submit to this Journal
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Proceeding Paper

A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones †

by
Anastasia A. Fesenko
and
Anatoly D. Shutalev
*
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Ave., 119991 Moscow, Russia
*
Author to whom correspondence should be addressed.
†
Presented at the 22nd International Electronic Conference on Synthetic Organic Chemistry, 15 November–15 December 2018; Available Online: https://sciforum.net/conference/ecsoc-22.
Proceedings 2019, 9(1), 14; https://doi.org/10.3390/ecsoc-22-05683
Published: 14 November 2018
(This article belongs to the Proceedings of 22nd International Electronic Conference on Synthetic Organic Chemistry)
Browse Figures
Versions Notes

Abstract

:
A general stereoselective approach to previously unknown 1,2,4-triazepane-3-thiones/ones based on reduction or reductive alkylation of readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones has been developed. The approach involved treatment of tetrahydrotriazepines with sodium cyanoborohydride in MeOH at pH 3 or with sodium borohydride and excess of carboxylic acid in tetrahydrofuran to give 1-unsubstituted or 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones, respectively. The latter were also prepared by reaction of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones with sodium cyanoborohydride and aldehyde in MeOH in the presence of AcOH.

1. Introduction

Development of efficient approaches to rare heterocyclic scaffolds is a fundamental challenge of organic synthesis and medicinal chemistry. 1,2,4-Triazepines, particularly 1,2,4-triazepin-3-ones/ thiones are representatives of these scaffolds [1,2,3,4,5,6]. They are of great interest because of their diverse pharmacological properties. For example, 1,2,4-triazepin-3-ones/thiones are effective antagonists of parathyroid hormone 1 (PTH1R) [7] and holecystokinin hormone 2 (CCK2) [8,9] receptors. Some of them possess antioxidant [10], antipsychotic [11,12], and HIV protease inhibitory activities [13,14,15].
The reported syntheses of 1,2,4-triazepin-3-ones/thiones include the reaction of β-isocyanato and β-isothiocyanato ketones with hydrazines [16,17,18,19,20,21,22,23,24], condensation of semicarbazides and thiosemicarbazides with various 1,3-dicarbonyl compounds or their derivatives [10,25,26,27,28,29,30,31,32,33], reaction of arylidene ketones with N2H4·2HNCS [34], addition of semicarbazides and thiosemicarbazides to α,β-unsaturated carbonyl compounds or their synthetic equivalents [35,36,37,38,39], reaction of γ-hydrazino-substituted amines with phosgene equivalents [8,13,14,15,40], and intramolecular cyclization of 4-(γ-oxoalkyl)semicarbazides and 4-(γ-oxoalkyl)thiosemicarbazides or their derivatives [17,22,41,42]. Generally, these methods give access to 1,2,4-triazepin-2- ones/thiones with one or two double bonds in the 7-membered ring. Their saturated representatives, particularly 1,2,4-triazepan-3-ones/thiones 1 (Figure 1) remain practically inaccessible since the methods designed to produce these compounds mostly result in smaller-sized rings. For example, the condensation of 2-substituted thiosemicarbazides with 2,2-disubstituted malonyl chlorides was reported to give 5,7-dioxo-1,2,4-triazepane-3-thiones [43,44]. However, reinvestigation of this reaction showed that in most cases the only products formed were azetidine-2,4-diones [32], with the exception of the reaction between 2-phenylthiosemicarbazide and 2,2-diethyl malonyl chloride affording the corresponding azetidine-2,4-dione (59%) along with 6,6-diethyl-5,7-dioxo-2-phenyl-1,2,4-triazepane-3-thione (2%).
The only relevant approach to triazepanes is based on the reaction of poorly available chiral non-racemic γ-hydrazino-substituted amines with phosgene equivalents to give the derivatives of 6-hydroxy-1,2,4-triazepan-3-ones. It should be noted that these compounds are the key precursors for preparation of potent nonpeptidic HIV protease inhibitors (e.g., 2) [13,14,15].
Syntheses of triazepane-3-thiones/ones without functional groups at the 5, 6, and 7 positions, cyclic thiosemicarbazides, and semicarbazides, have not been reported. Thus, the development of reliable and practical approaches to non-functionalized triazepane-3-thiones/ones is of great interest from the viewpoint of synthetic, theoretical, and medicinal chemistry. We rationalized that these compounds could be prepared by reductive transformations of 2,4,5,6-tetrahydro-3H-1,2,4-triazepin- 2-ones/thiones. Previously, we developed effective syntheses of the latter based on acid-catalyzed cyclization of 4-(3-aryl-3-oxopropyl)(thio)semicarbazides and their hydrazones [18,42] or base-promoted ring expansion of 3-amino-4-hydroxyhexahydropyrimidine-2-thiones [19].
Here, we describe general stereoselective syntheses of previously unknown 1-unsubstituted or 1-alkyl substituted 1,2,4-triazepane-3-thiones/ones via reduction or reductive alkylation of tetrahydro-3H-1,2,4-triazepine-3-thiones/ones.

2. Results and Discussion

Readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones 3a–k [18,19,42] served as starting material for the present investigation. Among a large variety of reductants which could be used for C=N double bond reduction [45,46,47,48,49,50] we chose sodium cyanoborohydride [51,52,53,54,55]. We have found that triazepines 3a–k smoothly reacted with NaBH3CN (1.00–1.61 equiv.) in MeOH under slightly acidic conditions (pH about 3) at room temperature to give the corresponding 1-unsubstituted triazepanes 4a–k in high yields (Scheme 1, Table 1). The pH was maintained by the addition of 2N HCl in MeOH with methyl orange as an internal indicator.
The reduction rate strongly depended on the structure of triazepines 3a–k and generally increased in the case of triazepin-3-ones compared with triazepine-3-thiones (Table 1; entry 5 vs. entry 6; entry 8 vs. entry 9; entry 10 vs. entry 11), 5-monosubstituted triazepines compared with 5,5-disubstituted ones (entry 3 vs. entries 4, 5, and 6; entry 7 vs. entry 8), and monocyclic triazepines compared with bicyclic ones (entries 1 and 2 vs. entries 4, 5, 6, and 8).
Reduction of the C=N bond in 3a–k results in formation of a new stereocenter at the C7 atom. Diastereoselectivity of this reaction varies from good to excellent (Table 1). Due to strong 1,2-asymmetric induction bicyclic triazepines 3d–f,h gave practically single (6R*,7S*)-diastereomers of triazepanes 4d–f,h with cis-relationship between two rings (cis/trans ≥ 98:2) (entries 4–6, and 8). With triazepine 3i the reaction diastereoselectivity slightly decreased, and a mixture of cis- and trans-isomers of 4i was obtained in a ratio of 88:12 (entry 9). Reduction of diphenyl-substituted monocyclic triazepines 3j,k showed further decrease in selectivity to result in mixtures of cis- and trans-diastereomers of triazepanes 4j,k in a ratio of 74:26 and 82:18, respectively (entries 10 and 11).
Next, we studied reduction of bicyclic 5-methyl triazepines 3c and 3g possessing two stereocenters which were obtained as mixtures of two diastereomers in a ratio of 92:8 and 60:40, respectively [19]. We have found that practically single (5R*,6R*,7R*)-diastereomer (>96%) of 4c formed in 94% yield from 3c (entry 3) and a 60:40 mixture of (5R*,6R*,7R*)- and (5R*,6S*,7S*)-diastereomers of 4g formed in 84% yield from 3g (entry 7). With both triazepines 3c and 3g strong 1,2-asymmetric induction led exclusively to triazepanes 4c,g with cis-relationship between two rings. Based on these data, the relative configuration of the major and minor isomers of starting compounds 3c,g could be unambiguously assigned as (5R*,5aR*) and (5S*,5aR*), respectively [19].
We suppose that the first step of the reduction of triazepines 3a–k under the described conditions is protonation of either the oxo/thioxo-group or the imino nitrogen affording hydrochlorides 5a–k or 6a–k, respectively (Scheme 2).
The density functional theory calculations performed at the B3LYP/6-311++G(d,p) level of theory for cations 5d,h,i,k and 6d,h,i,k with pseudo-axial and pseudo-equatorial orientation of the 5-Ph group (for 5k and 6k) or C6-CH2 bond (for 5d,h,i and 6d,h,i) using the polarizable continuum model showed that the N-protonated cations 6d,h,i,k are significantly more stable than the corresponding O- or S-protonated cations 5d,h,i,k (1.8–8.1 kcal/mol in MeOH). Therefore, formation of 5a–k can be excluded. The final step of the reaction is hydride transfer from NaBH3CN to the initially generated hydrochlorides 6a–k to give the target products 4a–k.
High diastereoselectivity in the reduction of 3c–k can be explained in terms of steric approach control. The equatorial attack of the reducing reagent to the imine carbon of intermediate cations 6c–k is preferable. The axial attack is complicated by van der Waals repulsions with two axial cyclohexane hydrogens in 6g–i, two pseudo-axial cyclopentane hydrogens in 6c–f or pseudo-axial 5-H hydrogen in 6j,k. This conclusion is confirmed by the DFT B3LYP/6-311++G(d,p) optimized geometries (in MeOH) of the most stable conformers of cations 6d,h,i,k with pseudo-axial and pseudo-equatorial position of the 5-Ph group (for 6k) or C6-CH2 bond (for 6d,h,i). Three representative examples with favored (a) and unfavored (b) attack of BH3CN-anion to the equatorial conformers of cations 6d,i,k are shown in Figure 2.
Crude triazepanes 4a–k were purified by crystallization (for 4a,d–f,h–j) or using silica gel column chromatography followed by crystallization (for 4b,c,g,k). It should be noted that after purification triazepanes 4c–f,h,j,k were obtained as practically single diastereomers (dr ≥ 95%).
The structure of compounds 4a-k was established by spectroscopic data. The 1H NMR spectra of 4a–k in DMSO-d6 show a long-range coupling between the (thio)amide N(2)H and N(4)H protons (4J = 2.0–2.5 Hz) that indicates their one-plane W-shaped arrangement. Similar long-range couplings are characteristic of N-unsubstituted (thio)ureide-containing heterocycles, e.g., 2,3,4,5-tetrahydro- and 2,3-dihydro-1H-1,3-diazepin-2-ones [56,57,58,59,60], hexahydro- and 1,2,3,4-tetrahydropyrimidine-2-thiones/ones [56,57,58,59,60,61,62,63,64,65,66,67], 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones [18,19,42]. Signal of the N(1)H proton in 4a–k appears as a doublet of doublets at 4.23–6.36 ppm with vicinal couplings 3JN(1)H,N(2)H = 0–3.5 and 3JN(1)H,H-7 = 4.2–11.1 Hz. The relative configurations of the stereogenic centers in 4c,d,f,i–k and the minor isomers of 4g,h were assigned based on the analysis of couplings between protons of the triazepane ring. For example, high values of vicinal couplings between the H-5 and H-6 protons (10.5 Hz) and between the H-7 and N(1)H protons (10.8 Hz) in 4c indicate that these protons are antiperiplanar, and therefore, this compound has (5R*,6R*,7R*)-configuration. The cis-relationship between the cyclopentane and triazepane rings in 4c is also confirmed by a relatively high value of vicinal coupling between the H-6 and H-7 protons (8.2 Hz). High values of vicinal couplings 3JH-5,H-6 = 10.5 Hz and 3JH-6,H-7 = 10.8 Hz observed in the 1H NMR spectrum of the minor diastereomer of 4j prove that two phenyl groups have cis-arrangement. The major diastereomer of 4j has trans-configuration with a pseudo-axial orientation of the 5-Ph group (3JN(4)H,H-5 = 5.2, 3JH-5,H-6 = 2.5 Hz) and a pseudo-equatorial orientation of the 7-Ph group (3JH-6,H-7 = 9.2 Hz).
Two alternative procedures were developed for preparation of 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones. The first involves reductive alkylation of 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones 3 with sodium borohydride in carboxylic acid media [68,69,70,71]. We found that monocyclic triazepines 3a,b smoothly reacted with NaBH4 (6 equiv.) in the presence of AcOH or EtCOOH (60.3–61.9 equiv.) in THF at room temperature for 23.5–24 h to give the corresponding 1-ethyl- or 1-propyltriazepanes 7a,b,e,f in 50–90% yields (Scheme 3; Table 2, entries 1, 2, 6, and 7).
Under similar conditions (THF, rt, 24 h), the reaction of diphenyl triazepine 3k with NaBH4 (5.9 equiv.) in the presence of AcOH (63.4 equiv.) gave a mixture of starting material 3k and 1-ethyltriazepane 7n in a ratio of 21:79, respectively. This reaction was completed with 10 equivalents of NaBH4 and 108.3 equivalents of AcOH to produce the target 7n in 94% yield with excellent trans-diastereoselectivity (trans:cis = 98:2, Table 2, entry 16). Higher stereoselectivity in the reduction of 3k with NaBH(OAc)3, in situ generated from NaBH4 and AcOH [68], compared with NaBH3CN (trans:cis = 82:18, Table 1, entry 11) can be explained in terms of steric approach control (see Figure 2) considering a greater steric bulk of reducing reagent in the first case.
Cyclohexane-fused triazepine 3g [a 60:40 mixture of (5R*,5aR*)- and (5S*,5aR*)-isomers] reacted with NaBH4 (6.1 equiv.) in the presence of AcOH (65.4 equiv.) or EtCOOH (62.2 equiv.) in THF (rt, 24 h) with very high stereoselectivity to give mixtures (5R*,6R*,7R*)- and (5S*,6R*,7R*)-diastereomers (cis-relationship between two rings) of triazepanes 7k,l in a ratio of 61:39 and 58:42, respectively (entries 13 and 14). Reduction of cyclopentane-fused triazepine 3c also proceeded with very high stereoselectivity but the reaction rate relatively decreased. Under optimized conditions, the reaction between this compound [a 92:8 mixture of (5R*,5aR*)- and (5S*,5aR*)-isomers] and NaBH4 (10 equiv.) in the presence of AcOH (104 equiv.) (THF, rt, 24 h) afforded a 91:9 mixture of (5R*,6R*,7R*)- and (5S*,6R*,7R*)-diastereomers of 7g with cis-fused rings (entry 8).
The alternative approach to 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones 7 involves reductive alkylation of their 1-unsubstituted analogs 4 under the action of aldehyde and NaBH3CN in the presence of AcOH (Scheme 3). Treatment of 4a,c,e,h with aliphatic aldehydes (5.8–6.4 equiv.), NaBH3CN (1.5–1.6 equiv.) and AcOH (1.5 equiv.) in MeOH at room temperature for 2 h resulted in the corresponding triazepanes 7b,c,g,h,j,m in high yields (Table 2, entries 3, 4, 9, 10, 12, and 15). Under the same conditions, compounds 4a,e were reacted with benzaldehyde (6.1 equiv.), NaBH3CN (3.1–3.6 equiv.) and AcOH (3.0–3.1 equiv.) to give triazepanes 7d,i in 90 and 93% yields, respectively (entries 5 and 11).
Generally, the two-step approach to 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones (3 → 4 → 7) was more effective. For instance, following this method compound 7g was obtained from 3c in 82% overall yield, while direct reductive alkylation of 3c with the NaBH4/AcOH system gave 7g only in 31% yield.
The structures of compounds 7a–n were confirmed by spectroscopic data. The relative configurations of the stereogenic centers in 7g–n were assigned by analysis of proton coupling constants in the triazepane ring as described above for compounds 4.

3. Conclusions

A convenient stereoselective synthesis of N-unsubstituted 1,2,4-triazepane-3-thiones/ones based on the reduction of readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones with sodium cyanoborohydride in MeOH at pH 3 has been developed. Stereochemistry of the reduction was explained in terms of steric control approach of BH3CN-anion to N1-protonated substrate. The obtained 1,2,4-triazepane-3-thiones/ones were converted into 1-alkyl-substituted derivatives by reductive alkylation with sodium cyanoborohydride and aldehyde in MeOH in the presence of AcOH. Alternatively, 1-alkyl-1,2,4-triazepane-3-thiones/ones were prepared with high stereoselectivity by treatment of tetrahydrotriazepines with sodium borohydride and excess of carboxylic acid in THF.

Acknowledgements

This research was financially supported by the Russian Foundation for Basic Research (Grant No. 19-316-70006).

References and Note

  1. Sharp, J.T. Seven-membered Rings with Two or More Heteroatoms. In Comprehensive Heterocyclic Chemistry; Katritzky, A.R., Rees, C.W., Eds.; Pergamon: Oxford, UK, 1984; Volume 7, pp. 593–651. [Google Scholar]
  2. Tsuchiya, T. Seven-membered Rings with Three Heteroatoms 1,2,4. In Comprehensive Heterocyclic Chemistry II; Katritzky, A.R., Rees, C.W., Scriven, E.F.V., Eds.; Elsevier: Oxford, UK, 1996; Volume 9, pp. 309–331. [Google Scholar]
  3. Yranzo, G.I.; Moyano, E.L. Seven-membered Rings with Three Heteroatoms 1,2,4. In Comprehensive Heterocyclic Chemistry III; Katritzky, A.R., Ramsden, C.A., Scriven, E.F.V., Taylor, R.J.K., Eds.; Elsevier: Amsterdam, The Netherlands, 2008; Volume 13, pp. 399–430. [Google Scholar]
  4. Peet, N.P. Monocyclic and Condensed Triazepines and Tetrazepines. In The Chemistry of Heterocyclic Compounds; Rosowsky, A., Ed.; John Wiley: New York, NY, USA, 1984; Volume 43, Part 2; pp. 719–842. [Google Scholar]
  5. Léna, G.; Guichard, G. Synthetic Methods for the Preparation of Triazepandiones and Review of their Applications. Curr. Org. Chem. 2008, 12, 813–835. [Google Scholar] [CrossRef]
  6. Elattar, K.M.; Abozeid, M.A.; Mousa, I.A.; El-Mekabaty, A. Advances in 1,2,4-triazepines chemistry. RSC Adv. 2015, 5, 106710–106753. [Google Scholar] [CrossRef]
  7. McDonald, I.M.; Austin, C.; Buck, I.M.; Dunstone, D.J.; Gaffen, J.; Griffin, E.; Harper, E.A.; Hull, R.A.D.; Kalindjian, S.B.; Linney, I.D.; et al. Discovery and Characterization of Novel, Potent, Non-Peptide Parathyroid Hormone-1 Receptor Antagonists. J. Med. Chem. 2007, 50, 4789–4792. [Google Scholar] [CrossRef]
  8. McDonald, I.M.; Austin, C.; Buck, I.M.; Dunstone, D.J.; Griffin, E.; Harper, E.A.; Hull, R.A.D.; Kalindjian, S.B.; Linney, I.D.; Low, C.M.R.; et al. Novel, Achiral 1,3,4-Benzotriazepine Analogues of 1,4-Benzodiazepine-Based CCK2 Antagonists That Display High Selectivity over CCK1 Receptors. J. Med. Chem. 2006, 49, 2253–2261. [Google Scholar] [CrossRef]
  9. Kaur, K.; Talele, T.T. 3D QSAR studies of 1,3,4-benzotriazepine derivatives as CCK2 receptor antagonists. J. Mol. Graph. Model. 2008, 27, 409–420. [Google Scholar] [CrossRef] [PubMed]
  10. Sankaran, M.; Kumarasamy, C.; Chokkalingam, U.; Mohan, P.S. Synthesis, antioxidant and toxicological study of novel pyrimido quinoline derivatives from 4-hydroxy-3-acyl quinolin-2-one. Bioorg. Med. Chem. Lett. 2010, 20, 7147–7151. [Google Scholar] [CrossRef]
  11. Ibrahim, S.M.; Abo-Kul, M.; Soltan, M.K.; Barakat, W.; Helal, A.S. Synthesis and Biological Screening of New Derivatives of 2,3-dihydro quinazolin-4(1H)-one and Benzotriazepin- 5(2H)-one for Central Nervous System Activity. Med. Chem. 2014, 4, 351–356. [Google Scholar] [CrossRef]
  12. Ibrahim, S.M.; Baraka, M.M.; El-Sabbagh, O.I.; Kothayer, H. Synthesis of new benzotriazepin-5(2H)-one derivatives of expected antipsychotic activity. Med. Chem. Res. 2013, 22, 1488–1496. [Google Scholar] [CrossRef]
  13. Zhao, C.; Sham, H.L.; Sun, M.; Stoll, V.S.; Stewart, K.D.; Lin, S.; Mo, H.; Vasavanonda, S.; Saldivar, A.; Park, C.; et al. Synthesis and activity of N-acyl azacyclic urea HIV-1 protease inhibitors with high potency against multiple drug resistant viral strains. Bioorg. Med. Chem. Lett. 2005, 15, 5499–5503. [Google Scholar] [CrossRef] [PubMed]
  14. Sham, H.L.; Zhao, C.; Stewart, K.D.; Betebenner, D.A.; Lin, S.; Park, C.H.; Kong, X.-P.; Rosenbrook, W.; Herrin, T.; Madigan, D.; et al. A Novel, Picomolar Inhibitor of Human Immunodeficiency Virus Type 1 Protease. J. Med. Chem. 1996, 39, 392–397. [Google Scholar] [CrossRef]
  15. Hodge, C.N.; Fernandez, C.H.; Jadhav, P.K.; Lam, P.Y. Preparation of substituted caprolactams and derivatives useful for treatment of HIV disease. WO 9422840, 1994. Chem. Abstr. 1994, 123, 33104. [Google Scholar]
  16. Lantzsch, R.; Arlt, D. Herstellung und Reaktionen von 1,1-Dimethyl-3-oxobutyl-isocyanat. Synthesis 1977, 11, 756–757. [Google Scholar] [CrossRef]
  17. Mosher, W.A.; Toothill, R.B. Investigation of Routes to Indeno[2,1-f]-2H-1,2,4-triazepinediones. J. Heterocycl. Chem. 1971, 8, 209–214. [Google Scholar] [CrossRef]
  18. Fesenko, A.A.; Grigoriev, M.S.; Shutalev, A.D. Synthesis of aryl substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones starting from chalcone-derived β-isothiocyanato ketones. Tetrahedron 2016, 72, 7952–7967. [Google Scholar] [CrossRef]
  19. Fesenko, A.A.; Shutalev, A.D. Base-promoted ring expansion of 3-aminopyrimidine-2-thiones into 1,2,4-triazepine-3-thiones. Tetrahedron 2016, 72, 2560–2573. [Google Scholar] [CrossRef]
  20. Danilkina, N.A.; Mikhaylov, L.E.; Ivin, B.A. Reaction of Acetylenedicarboxylic Acids Esters with 4,5-Dihydro-1H-pyrazole-1-carbothioamides and 3,4,5,6-Tetrahydro-2H-1,2,4-triazepine-3-thiones. Chem. Heterocycl. Compd. 2011, 47, 886–900. [Google Scholar] [CrossRef]
  21. Rezessy, B.; Zubovics, Z.; Kovács, J.; Tóth, G. Synthesis and structure elucidation of new thiazolotriazepines. Tetrahedron 1999, 55, 5909–5922. [Google Scholar] [CrossRef]
  22. Richter, P.; Steiner, K. Chalcone as Starting Material for Synthesis of 1,2,4-Triazepines. In Studies in Organic Chemistry; van der Plas, H.C., Ötvös, L., Simonyi, M., Eds.; Elsevier: Amsterdam, The Netherlands, 1984; Volume 18, pp. 217–220. [Google Scholar]
  23. Neidlein, R.; Ober, W.D. Synthesen von Siebenerringsystemen aus substituierten Isothiocyanaten und Hydrazinen. Monatsh. Chem. 1976, 107, 1251–1258. [Google Scholar] [CrossRef]
  24. Zigeuner, G.; Fuchsgruber, A.; Wede, F. Notiz zur Struktur des Umsetzungsproduktes von 4-Isothiocyanato-4-methyl-2-pentanon mit Hydrazin—Uber das 2,4,5,6-Tetrahydro-5,5,7-trimethyl- 3H-1,2,4-triazepin-3-thion. Monatsh. Chem. 1975, 106, 1495–1497. [Google Scholar] [CrossRef]
  25. Hassan, M.M.; Othman, E.S.; Abass, M. 3-Acetyl-4-methylthioquinolin-2(1H)-one as useful synthon intermediate for synthesis of some new quinolinones. Res. Chem. Intermed. 2013, 39, 1209–1122. [Google Scholar] [CrossRef]
  26. Chaudhary, A.; Joshi, S.C.; Singh, R.V. Studies on Therapeutically Relevant Tin(II) and Lead(II) Complexes of Schiff Base Macrocyclic Ligands Containing Thiosemicarbazone Moiety. Main Group Met. Chem. 2004, 27, 59–70. [Google Scholar] [CrossRef]
  27. Ibrahim, S.S.; El-Gendy, Z.M.; Allimony, H.A.; Othman, E.S. New Quinolones and Naphthyridinones Bearing Heterocyclic Rings. Chem. Papers 1999, 53, 53–64. [Google Scholar]
  28. Hasnaoui, A.; Lavergne, J.-P.; Viallefont, P. Condensation des composés β-dicarbonylés avec les thiosemicarbazides. Recl. Trav. Chim. Pays-Bas 1980, 99, 301–306. [Google Scholar] [CrossRef]
  29. Hasnaoui, A.; Lavergne, J.-P.; Viallefont, P. Syntheses de nouvelles triazépines-1,2,4. J. Heterocycl. Chem. 1978, 15, 71–75. [Google Scholar] [CrossRef]
  30. Stanovnik, B.; Tišler, M. Zur Reaktion von 1,1,3,3-Tetraäthoxypropan mit Thiosemicarbaziden. Naturwissenschaften 1965, 52, 207. [Google Scholar] [CrossRef]
  31. Losse, G.; Farr, W. Synthese und Reaktionen der Heptriazinone. J. Prakt. Chem. 1959, 8, 298–305. [Google Scholar] [CrossRef]
  32. Ebnöther, A.; Jucker, E.; Rissi, E.; Rutschmann, J.; Schreier, E.; Steiner, R.; Süess, R.; Vogel, A. Über Azetidin-2,4-dione (Malonimide). Helv. Chim. Acta 1959, 42, 918–955. [Google Scholar] [CrossRef]
  33. Losse, G.; Hessler, W.; Barth, A. Ringschlussreaktionen mit Thiosemicarbaziden. Chem. Ber. 1958, 91, 150–157. [Google Scholar] [CrossRef]
  34. Seebacher, W.; Michl, G.; Weis, R. Synthesis of new triazepinethiones. Tetrahedron Lett. 2002, 43, 7481–7483. [Google Scholar] [CrossRef]
  35. Hassan, A.A.; Bebair, T.M.; El-Gamal, M. Synthesis of pyrazolylthiazole and pyrazolyl-1,2,4-triazepine derivatives. J. Chem. Res. 2014, 38, 27–31. [Google Scholar] [CrossRef]
  36. Aly, A.A.; Hassan, A.A.; El-Sheref, E.M.; Mohamed, M.A.; Brown, A.B. Conventional and Microwave Irradiation Assisted Synthesis of New 1,2,4-Triazepine-3-thiones. J. Heterocycl. Chem. 2008, 45, 521–526. [Google Scholar] [CrossRef]
  37. El-Helby, A.A.; Amin, M.A.; El-Sawah, M.M.; Bayoni, A.H.; El-Azab, A.S.; Sherbiny, F.F. Synthesis and Microbiological Testing of Some New Derivatives of Compounds Containing Active Methylene Group. J. Saudi Chem. Soc. 2006, 10, 77–93. [Google Scholar]
  38. Abdel-Ghany, H.; Khodairy, A.; Moustafa, H.M. Novel Synthesis of Some Spiro Heterocycles Derived from 3-Hydroxy-3-(2-oxocyclohexyl)-indolin-2-one. Synth. Commun. 2000, 30, 1257–1268. [Google Scholar] [CrossRef]
  39. Kobayashi, M.; Tanaka, J.; Katori, T.; Marsuura, M.; Yamashita, M.; Kitagawa, I. The Absolute Stereostructure of Swinholide A, a Potent Cytotoxic Dimeric Macrolide from the Okinawan Marine Sponge Theonella swinhoei. Chem. Pharm. Bull. 1990, 38, 2409–2418. [Google Scholar] [CrossRef]
  40. Hosmane, R.S.; Bhadti, V.S.; Lim, B.B. Synthesis of a Novel Ring-Expanded Xanthine Analogue and Several Methyl or Benzyl Derivatives Containing the 5:7-Fused Imidazo[4,5-e][1,2,4]triazepine Ring System. Synthesis 1990, 1990, 1095–1100. [Google Scholar] [CrossRef]
  41. Trafimova, L.A.; Zimin, M.O.; Shutalev, A.D. Thiocarbamate-based synthesis of 2,4,5,6-tetrahydro-3H- 1,2,4-triazepine-3-thiones. J. Chem. Res. 2017, 41, 149–156. [Google Scholar] [CrossRef]
  42. Fesenko, A.A.; Shutalev, A.D. Different modes of acid-catalyzed cyclization of 4-(γ-oxoalkyl)semicarbazide hydrazones: 7-membered versus 14-membered cyclic semicarbazones formation. Tetrahedron 2015, 71, 9528–9543. [Google Scholar] [CrossRef]
  43. Losse, G.; Uhlig, H. Neue Siebengliedrige Heterocyclen auf Thiosemicarbazidbasis. Chem. Ber. 1957, 90, 257–260. [Google Scholar] [CrossRef]
  44. Losse, G.; Wottgen, E.; Just, H. Substituierte 7gliedrige Heterocyclen mit mehreren Heteroatomen. J. Prakt. Chem. 1958, 7, 28–37. [Google Scholar] [CrossRef]
  45. Hutchins, R.O.; Hutchins, M.K. Reduction of C=N to CHNH by Metal Hydrides. In Comprehensive Organic Synthesis; Trost, B.M., Fleming, I., Eds.; Pergamon: Oxford, UK, 1991; Volume 8, pp. 25–78. [Google Scholar]
  46. Hemmer, R.; Lürken, W. Amine. In Houben-Weyl Methods of Organic Chemistry; Thieme: Stuttgart, Germany, 1992; Volume E16d, pp. 646–1234. [Google Scholar]
  47. Andersson, P.G.; Munslow, I.J. (Eds.) Modern Reduction Methods; Wiley-VCH Verlag: Weinheim, Germany, 2008. [Google Scholar]
  48. Nugenta, T.C.; El-Shazly, M. Chiral Amine Synthesis - Recent Developments and Trends for Enamide Reduction, Reductive Amination, and Imine Reduction. Adv. Synth. Catal. 2010, 352, 753–819. [Google Scholar] [CrossRef]
  49. Layer, R.W. The Chemistry of Imines. Chem. Rev. 1963, 63, 489–510. [Google Scholar] [CrossRef]
  50. Tripathi, R.P.; Verma, S.S.; Pandey, J.; Tiwar, V.K. Recent development on catalytic reductive amination and applications. Curr. Org. Chem. 2008, 12, 1093–1115. [Google Scholar] [CrossRef]
  51. Hutchins, R.O.; Hutchins, M.K.; Crawley, M.L. Sodium Cyanoborohydride. In e-EROS: Encyclopedia of Reagents for Organic Synthesis; John Wiley & Sons: Weinheim, Germany, 2007. [Google Scholar] [CrossRef]
  52. Seyden-Penne, J. Reductions by the Alumino- and Borohydrides in Organic Synthesis, 2nd ed.; Wiley-VCH: New York, NY, USA, 1997. [Google Scholar]
  53. Lane, C.F. Sodium Cyanoborohydride—A Highly Selective Reducing Agent for Organic Functional Groups. Synthesis 1975, 3, 135–146. [Google Scholar] [CrossRef]
  54. Hutchins, R.O.; Natale, N.R. Cyanoborohydride. Utility and Applications in Organic Synthesis. A Review. Org. Prep. Proced. Int. 1979, 11, 201–246. [Google Scholar] [CrossRef]
  55. Borch, R.F.; Bernstein, M.D.; Durst, H.D. The Cyanohydridoborate Anion as a Selective Reducing Agent. J. Am. Chem. Soc. 1971, 93, 2897–2904. [Google Scholar] [CrossRef]
  56. Fesenko, A.A.; Grigoriev, M.S.; Shutalev, A.D. Nucleophile-Mediated Ring Expansion of 5-Acyl- substituted 4-Mesyloxymethyl-1,2,3,4-tetrahydropyrimidin-2-ones in the Synthesis of 7-Membered Analogues of Biginelli Compounds and Related Heterocycles. J. Org. Chem. 2017, 82, 8085–8110. [Google Scholar] [CrossRef] [PubMed]
  57. Fesenko, A.A.; Shutalev, A.D. 2,3-Dihydro-1H-1,3-diazepin-2-ones: synthesis and novel rearrangements into pyrrole derivatives. Tetrahedron Lett. 2014, 55, 1416–1420. [Google Scholar] [CrossRef]
  58. Fesenko, A.A.; Trafimova, A.A.; Shutalev, A.D. Synthesis of functionalized tetrahydro-1,3-diazepin-2-ones and 1-carbamoyl-1H-pyrroles via ring expansion and ring expansion/ring contraction of tetrahydropyrimidines. Org. Biomol. Chem. 2012, 10, 447–462. [Google Scholar] [CrossRef]
  59. Fesenko, A.A.; Shutalev, A.D. Nucleophile-mediated ring expansion of 4-chloromethyl- and 4-mesyloxymethyl-5-tosyl-1,2,3,4-tetrahydropyrimidin-2-ones to 6-tosyl-2,3,4,5-tetrahydro-1H-1,3- diazepin- 2-ones: the effect of the leaving group and the substituent at C6. Tetrahedron 2011, 67, 6876–6882. [Google Scholar] [CrossRef]
  60. Fesenko, A.A.; Tullberg, M.L.; Shutalev, A.D. General approach to 6-tosyl-2,3,4,5-tetrahydro- 1H-1,3-diazepin-2-ones via nucleophile-mediated ring expansion of tetrahydropyrimidines. Tetrahedron 2009, 65, 2344–2350. [Google Scholar] [CrossRef]
  61. Solovyev, P.A.; Fesenko, A.A.; Shutalev, A.D. A new synthesis of 4- or/and 6-CF3-containing hexahydro- and 1,2,3,4-tetrahydropyrimidin-2-ones. J. Fluor. Chem. 2016, 182, 28–33. [Google Scholar] [CrossRef]
  62. Fesenko, A.A.; Shutalev, A.D. A novel access to pyrido[4,3-d]pyrimidine scaffold via Staudinger/intramolecular aza-Wittig reaction of 5-acyl-4-(β-azidoalkyl)-1,2,3,4-tetrahydropyrimidin- 2-ones. Tetrahedron 2014, 70, 5398–5414. [Google Scholar] [CrossRef]
  63. Fesenko, A.A.; Shutalev, A.D. Synthesis of γ-Azido-β-Ureido Ketones and their Transformation into Functionalized Pyrrolines and Pyrroles via Staudinger/aza-Wittig Reaction. J. Org. Chem. 2013, 78, 1190–1207. [Google Scholar] [CrossRef]
  64. Fesenko, A.A.; Dem’yachenko, E.A.; Fedorova, G.A.; Shutalev, A.D. A novel selective synthesis of β-isothiocyanato ketones through a Staudinger/aza-Wittig reaction of β-azido ketones. Monatsh. Chem. 2013, 144, 351–359. [Google Scholar] [CrossRef]
  65. Fesenko, A.A.; Solovyev, P.A.; Shutalev, A.D. A novel convenient synthesis of 5-acyl-1,2- dihydropyrimidin-2-ones via 4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones. Tetrahedron 2010, 66, 940–946. [Google Scholar] [CrossRef]
  66. Fesenko, A.A.; Shutalev, A.D. Diastereoselective synthesis of 5-benzylthio- and 5-mercaptohexahydropyrimidin-2-ones. Tetrahedron Lett. 2007, 48, 8420–8423. [Google Scholar] [CrossRef]
  67. Shutalev, A.D.; Kurochkin, N.N. A new approach to the synthesis of Biginelli compounds. Mendeleev Commun. 2005, 15, 70–72. [Google Scholar] [CrossRef]
  68. Gribble, G.W.; Nutaitis, C.F. Sodium Borohydride in Carboxylic Acid Media. A Review of the Synthetic Utility of Acyloxyborohydrides. Org. Prep. Proced. Int. 1985, 17, 317–384. [Google Scholar] [CrossRef]
  69. Abdel-Magid, A.F.; Carson, K.G.; Harris, B.D.; Maryanoff, C.A.; Shah, R.D. Reductive Amination of Aldehydes and Ketones with Sodium Triacetoxyborohydride. Studies on Direct and Indirect Reductive Amination Procedures. J. Org. Chem. 1996, 61, 3849–3862. [Google Scholar] [CrossRef]
  70. Baxter, E.W.; Reitz, A.B. Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents. Org. React. 2002, 59, 1–714. [Google Scholar]
  71. Abdel-Magid, A.F.; Mehrman, S.J. A Review on the Use of Sodium Triacetoxyborohydride in the Reductive Amination of Ketones and Aldehydes. Org. Proc. Res. Dev. 2006, 10, 971–1031. [Google Scholar] [CrossRef]
Proceedings 09 00014 g001
Figure 1. General formula of 1,2,4-triazepane-3-thiones/ones 1 and structure of nonpeptidic HIV protease inhibitor 2.
Figure 1. General formula of 1,2,4-triazepane-3-thiones/ones 1 and structure of nonpeptidic HIV protease inhibitor 2.
Proceedings 09 00014 g001
Proceedings 09 00014 sch001
Scheme 1. Synthesis of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones 4a–k.
Scheme 1. Synthesis of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones 4a–k.
Proceedings 09 00014 sch001
Proceedings 09 00014 sch002
Scheme 2. A plausible pathway for the reduction of 3a–k into 4a–k.
Scheme 2. A plausible pathway for the reduction of 3a–k into 4a–k.
Proceedings 09 00014 sch002
Proceedings 09 00014 g002
Figure 2. Favored (a) and unfavored (b) approach of BH3CN-anion to N-protonated triazepines: 6i (i), 6d (ii), and 6k (iii).
Figure 2. Favored (a) and unfavored (b) approach of BH3CN-anion to N-protonated triazepines: 6i (i), 6d (ii), and 6k (iii).
Proceedings 09 00014 g002
Proceedings 09 00014 sch003
Scheme 3. Synthesis of 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones 7a–n by the reductive alkylation.
Scheme 3. Synthesis of 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones 7a–n by the reductive alkylation.
Proceedings 09 00014 sch003
Table 1. Synthesis of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones 4a–k by reduction of 3a–k with NaBH3CN in MeOH at room temperature (pH 3) a.
Table 1. Synthesis of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones 4a–k by reduction of 3a–k with NaBH3CN in MeOH at room temperature (pH 3) a.
Entry3XRR1R2R3Equiv. of NaBH3CNTime (h)ProductIsolated Yield (%)cis/trans Ratio b
13aSMeMeHMe1.0014a93–
23bOMeMeHMe1.0014b54–
33c cSMeHCH2CH2CH21.0114c94– d
43dSMeMeCH2CH2CH21.483.174d88>99:1
53eSCH2CH2CH2CH2CH2CH21.613.174e92>99:1
63fOCH2CH2CH2CH2CH2CH21.4914f9199:1
73g eSMeHCH2CH2CH2CH21.0014g84– f
83hSMeMeCH2CH2CH2CH21.5014h9398:2
93iOMeMeCH2CH2CH2CH21.0114i9488:12
103jSPhHHPh1.5134j9926:74
113kOPhHHPh1.0014k9318:82
a Level of conversion of the starting material is 100%. b According to 1H NMR spectroscopic data for the crude product. c A 92:8 mixture of (5R*,5aR*)- and (5S*,5aR*)-diastereomers (ref. [19]). d A nearly pure (5R*,6R*,7R*)-diastereomer (>96%). e A 60:40 mixture of (5R*,5aR*)- and (5S*,5aR*)-diastereomers (ref. [19]). f A mixture of (5R*,6R*,7R*)- and (5R*,6S*,7S*)-diastereomers in a ratio of 60:40, respectively.
Table 2. Synthesis of 1-substituted 1,2,4-triazepane-3-thiones/ones 7a–n by the reductive alkylation of 3a–c,g,k and 4a,c,e,f,h a.
Table 2. Synthesis of 1-substituted 1,2,4-triazepane-3-thiones/ones 7a–n by the reductive alkylation of 3a–c,g,k and 4a,c,e,f,h a.
Entry3 or 4XRR1R2R3R4Reaction conditions b7Yield (%) cdr d
13aSMeMeHMeMeNaBH4 (6.0), AcOH (61.1), THF, rt, 24 h7a89–
23aSMeMeHMeEtNaBH4 (6.0), EtCOOH (61.9), THF, rt, 24 h7b90–
34aSMeMeHMeEtNaBH3CN (1.5), EtCHO (5.8), AcOH (1.5), MeOH, rt, 2 h7b90–
44aSMeMeHMePrNaBH3CN (1.5), PrCHO (6.0), AcOH (1.5), MeOH, rt, 2 h7c95–
54aSMeMeHMePhNaBH3CN (3.6), PhCHO (6.1), AcOH (3.0), MeOH, rt, 2 h7d90–
63bOMeMeHMeMeNaBH4 (6.0), AcOH (60.3), THF, rt, 24 h7e50–
73bOMeMeHMeEtNaBH4 (6.0), EtCOOH (60.6), THF, rt, 23.5 h7f50–
83c eSMeHCH2CH2CH2MeNaBH4 (10.1), AcOH (104.1), THF, rt, 24 h7g31– f
94cSMeHCH2CH2CH2MeNaBH3CN (1.6), MeCHO (6.4), AcOH (1.5), MeOH, rt, 2 h7g87>99:1
104eSCH2CH2CH2CH2CH2CH2EtNaBH3CN (1.5), EtCHO (6.1), AcOH (1.5), MeOH, rt, 2 h7h95>99:1
114eSCH2CH2CH2CH2CH2CH2PhNaBH3CN (3.1), PhCHO (6.1), AcOH (3.1), MeOH, rt, 2 h7i93>99:1
124f gOCH2CH2CH2CH2CH2CH2EtNaBH3CN (1.5), EtCHO (6.2), AcOH (1.5), MeOH, rt, 2 h7j6899:1
133g hSMeHCH2CH2CH2CH2MeNaBH4 (6.1), AcOH (65.4), THF, rt, 24 h7k85– i
143g hSMeHCH2CH2CH2CH2EtNaBH4 (6.1), EtCOOH (62.2), THF, rt, 24 h7l68– j
154h kSMeMeCH2CH2CH2CH2EtNaBH3CN (1.5), EtCHO (6.0), AcOH (1.5), MeOH, rt, 2 h7m96>99:1
163kOPhHHPhMeNaBH4 (10.1), AcOH (208.4), THF, rt, 24 h7n942:98
a Level of conversion of the starting material is 100%. b Number in parentheses is the number of equivalents. c Isolated yield. d dr—cis/trans-diastereomeric ratio according to 1H NMR spectroscopic data for the crude product. e A 92:8 mixture of (5R*,5aR*)- and (5S*,5aR*)-diastereomers (ref. [19]). f A 91:9 mixture of (5R*,6R*,7R*)- and (5S*,6R*,7R*)-diastereomers. g A 99:1 mixture of (6R*,7S*)- and (6R*,7R*)-diastereomers. h A 60:40 mixture of (5R*,5aR*)- and (5S*,5aR*)-diastereomers (ref. [19]). i A 61:39 mixture of (5R*,6R*,7R*)- and (5S*,6R*,7R*)-diastereomers. j A 58:42 mixture of (5R*,6R*,7R*)- and (5S*,6R*,7R*)-diastereomers. k A 98:2 mixture of (6R*,7S*)- and (6R*,7R*)-diastereomers.

Share and Cite

MDPI and ACS Style

Fesenko, A.A.; Shutalev, A.D. A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones. Proceedings 2019, 9, 14. https://doi.org/10.3390/ecsoc-22-05683

AMA Style

Fesenko AA, Shutalev AD. A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones. Proceedings. 2019; 9(1):14. https://doi.org/10.3390/ecsoc-22-05683

Chicago/Turabian Style

Fesenko, Anastasia A., and Anatoly D. Shutalev. 2019. "A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones" Proceedings 9, no. 1: 14. https://doi.org/10.3390/ecsoc-22-05683

APA Style

Fesenko, A. A., & Shutalev, A. D. (2019). A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones. Proceedings, 9(1), 14. https://doi.org/10.3390/ecsoc-22-05683

Article Metrics

Back to TopTop