Three-component reaction of imidazoles, cyanophenylacetylene, and chalcogens: stereoselective synthesis of 3-alkenyl-2-imidazolethiones and -selones
详细信息 查看全文
- 作者：Kseniya V. Belyaeva ; Ludmila V. Andriyankova ; Lina P. Nikitina ; Anastasiya G. Mal'kina ; Andrei V. Afonin ; Igor' A. Ushakov ; Irina Yu. Bagryanskaya ; Boris A. Trofimov
- 关键词：Heterocycles ; Alkynes ; Chalcogenes ; Zwitterions ; Multicomponent reactions
- 刊名：Tetrahedron
- 出版年：4 February, 2014
- 年：2014
- 卷：70
- 期：5
- 页码：1091-1098
- 全文大小：1062 K
文摘
The three-component reaction of 1-substituted imidazoles, cyanophenylacetylene, and elemental sulfur or selenium proceeds readily (for sulfur at room temperature without solvent, and for selenium in boiling MeCN) to stereoselectively afford 3-(Z)-cyanophenylethenyl-2-imidazolethiones or -selones in yields ranging 39-97% (for thiones) and 39-84% (for selones). In this reaction, tellurium is inactive both under the above conditions and upon heating (50-55聽掳C) in DMSO, instead, only the C(2)-vinylation of the imidazole ring in up to 98% yield takes place. The Z-stereoselectivity of the reaction is close to 100% (for sulfur) and reaches 91-99% (for selenium). The reaction involves the zwitterionic adduct of imidazoles with cyanophenylacetylene, which converts to the carbene via proton transfer (from the imidazole 2 position to the carbanionic site of the zwitterion) further reacting with chalcogens.