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,
2Laboratoire de Synthèse organique; Université de Nantes.
2, rue de la Houssinière, BP 92208-44322 Nantes Cedex 03, France
* Corresponding author. E-mail: email@example.com
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.