Exceptional isolation of both imine and enamine desmotropes of 4,1-benzothiazepines

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• 作者：Pé ; ter Csomó ; s ; Lajos Fodor ; Antal Csá ; mpai ; Pá ; l Sohá ; r
• 关键词：Desmotropy ; 4 ; 1-Benzothiazepine ; 1 ; 4-Benzothiazepine ; β ; -Lactam ; Ring transformation
• 刊名：Tetrahedron
• 出版年：2010
• 出版时间：24 April 2010
• 年：2010
• 卷：66
• 期：17
• 页码：3207-3213
• 全文大小：257 K

文摘

The desmotropy of differently substituted (R*)-3-ethoxycarbonyl-2-aryl-3,5-dihydro-4,1-benzothiazepines and 3-ethoxycarbonyl-2-aryl-1,5-dihydro-4,1-benzothiazepines was investigated. The target 4,1-benzothiazepines were obtained via the ring transformation of (2R*,2aS*)-2-chloro-2a-aryl-2,2a-dihydro-2H,4H-azeto[1,2-a][3,1]benzothiazin-1-ones with sodium ethoxide in ethanol. The β-amino ester intermediate of the ring-enlargement reaction was isolated. Surprisingly, the desmotropes obtained could be separated by column chromatography and proved to be unexpectedly stable in solution. Further comparative studies revealed the existence of only the enamine forms of regioisomeric 2-ethoxycarbonyl-3-aryl-4,5-dihydro-7,8-dimethoxy-1,4-benzothiazepine derivatives; in this case, no desmotropy occurred. The structures were proved by means of NMR and IR spectroscopy.