Document Type : Original Article

Authors

1 Medicinal Organic Chemistry Laboratory (MOCL), School of Pharmacy, Faculté des Sciences de la Santé, Universitéd'Abomey-Calavi, Campus du Champ de Foire, 01 BP 188, Cotonou, Bénin

2 Medicinal Chemistry (CMFA), Louvain Drug Research Institute, UCLouvain. 73, B1.73.10Av. E. Mounier B-1200 Brussels, Belgium, E.U.

3 Medicinal Chemistry (CMFA), Louvain Drug Research Institute, UCLouvain. 73, Av. E. Mounier B-1200 Brussels, Belgium, E.U.

4 Pharmacognosy Recherch Group (GNOS), Louvain Drug Research Institute, UCLouvain. 72, Bte B1.72.03, Av. E. Mounier B-1200 Brussels, Belgium, E.U.

5 Medicinal Chemistry, College of Pharmacy. Medical Science Building, P6-33, PO. Box 100485, University of Florida, Gainesville, FL 32610, USA

6 Medicinal Chemistry (CMFA), Louvain Drug Research Institute, UCLouvain. 73, B1.73.10 Av. E. Mounier B-1200 Brussels, Belgium, E.U.

Abstract

In a medicinal chemistry-driven drug discovery program aimed at synthesizing new topically-acting trypanocidal chemotherapeutic agents to treat the African trypanosomiasis, our research group became interested in new chemical entities bearing in their center a thiohydrazide (C=S) NHNH or thiosemicarbazide NH(C=S) NHNH central template flanked on both sides by lipophilic aryl moieties. In this context, benzopinacolone was found to react as a rather unusual acylating agent via a mechanism (addition/elimination) involving addition of the nucleophile (a thiosemicarbazide derivative), formation of a resulting tetrahedral adduct, and expulsion of a trityl anion moiety as leaving group, presumably through an anchimeric assistance effect by intram-olecular participation of the thioureido side-chain via hydrogen bond formation. The present incidental discovery should be considered at this level as a first inception and further work is now being directed at closely examining the detailed mechanism of this exceptional chemical pathway; in a reaction involving the unusual breaking of a carbon-carbon bond (carbon acid as leaving group) in the rate-determining step and involving the decomposition of the intermediate tetrahedral adduct to get the final unexpected N-thiobenzoyl-thiosemicarbazide.

Graphical Abstract

Anomalous reactivity of benzopinacolone towards 4-phenylthiosemicarbazide, a nucleophile endowed with alpha-effect

Keywords

1. U.C. Kasséhin, F.A. Gbaguidi, C.N. Kapanda, C. McCurdy, J.H. Poupaert, Afr. J. Pure Appl. Chem. 2014, 8, 110.
2. U.C. Kasséhin, F.A. Gbaguidi, C.N. Kapanda, C. McCurdy, J.H. Poupaert, J. Chem. Pharm. Res. 2015, 7, 48.
3. D. Herschlag, W.P. Jencks, J. Am. Chem. Soc.1990, 112, 1951.
4. E. Bunce, I.H. Um, Angew. Chem. 2008, 120, 7633.
5. S. Umamatheswari, S. Kabilan, J. Enzyme. Inhib. Med. Chem. 2011, 26, 9.
6. S.N. Pandeya, P. Yogeeswari, D. Sriram, E. Clercq, C. Pannecouque, M. Witvrouw, Chemotherapy. 1999, 4, 6.
7. H.D. Houngue, B.S. Aguida, U.C. Kasséhin, J.H. Poupaert, F.A. Gbaguidi, MOJ. Biorg. Org. Chem. 2017, 1, 1.
8. J.P. Mallari, W.A. Guiguemde, R.K. Guy, Med. Chem. Lett. 2009, 19, 3546.
9. U.C. Kasséhin, F.A. Gbaguidi, C. McCurdy, J.H. Poupaert, J. Chem. Pharm. Res .2014, 6, 607.
10. J.M. Sayer, W.P. Jencks, J. Am. Chem. Soc.1969, 91, 6353.
11. P.J. Dunn, Chem. Soc. Rev. 2012, 41, 1452.
12. P.T. Anastas, J.C. Warner, Green Chemistry: Theory and Practice. Ed. New-york, Oxford University Press, 1998. 1-135.
13. P.T. Anastas, N. Eghbali, Chem. Soc. Rev. 2010, 39, 301.
14. P.T. Anastas, M.M. Kirchhoff, Acc. Chem. Res. 2002, 35, 686.
15. P.T. Anastas, Aldrichimica. 2015, 48, 3.
16. P.T. Anastas, R.L. Green Chem. 2000, 2, 289.
17. R.A. Sheldon, Chem. Soc. Rev. 2012, 41, 1437.
18. G.G. Wubbels, Acc. Chem. Res. 1983, 16, 285.
19. E. Cohen, Rec. Trav. Chim. 1920, 39, 243.
20. G. Ciamician, P. Silber, Chemische Lichtwirkungen. Ber. 1900, 33, 2911.
21. L.C. Potey, S.B. Kosalge, R.S. Sarode, Int. J. Pharm. Drug. Anal. 2014, 2, 55.
22. G. Dormán, H. Nakamura, A. Pulsipher, G.D. Prestwich, Chem. Rev. 2016, 116, 1528.
23. M. Migita, Bcsj. 1932, 7, 334.
24. G. Zhao, T. Jiang, H. Gao, B. Han, J. Huanga, D. Suna, Green Chem. 2004, 6, 75.
25. M. Gómez-Martínez, A. Baeza, D.A. Alonso, Chem. Cat. Chem. 2017, 9, 1032.
26. N. Drosos, E. Ozkal, B. Cacherat, W. Thiel, B. Morandi, Angew. Chem. 2017, 56, 13377.
27. J.R. Beadle, S.H. Korzeniowski, D.E. Rosenberg, B.J. Garcia-Slanga, G.W. Gokel, J. Org. Chem. 1984, 49, 1594.
28. U.C. Kasséhin, F.A. Gbaguidi, C.N. Kapanda, C. McCurdy, A.K. Bigot, J.H. Poupaert, Afr. J. Pure Appl. Chem. 2013, 7, 325.