SUBSTITUTED 1-THIA-3-AZABUTADIENES The (4+2) REaction of cyclocondensAtion and cycloreversion with acetylenes: EXPERIMENTAL AND a MO Theoretical Study


T. Beguemsi1*, R. B. N’guessan1 , Lucie Bede1 , C. G. Téa1,  J. P. Pradère2, Y.T. N'guessan1

1Laboratoire de Chimie Organique Structurale: UFR SSMT Université de Cocody,
22 B.P 582 Abidjan 22, Côte- d'Ivoire

2Laboratoire de Synthèse organique; Université de Nantes.

2, rue de la Houssinière, BP 92208-44322 Nantes Cedex 03, France

* Corresponding author. E-mail:

Received: 08 May 2006; revised version accepted: 22 December 2006



     Diels-Alder (D-A) reactions of symmetrical and asymmetrical acetylenes with substituted 1-thia-3-azabutadienes were investigated. Our study is focused on the substituents in position 2, 4, 5 and 6, which have a key role in the retro-Diels-Alder reaction of thiazines. Transition states have been located and concerted and asynchronous transition states mechanism are confirmed.


Keywords: Diels-Alder, Thia-azabutadiene, Acetylene, Thiazines, Concerted, Transition state, Retro-Diels-Alder, Rich and  electrodeficient substituents, Mechanism, DFT.

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