Synthesis of 1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives by the reaction of 2-chloro-1,4-benzothiazin-3-ones with ‘push–pullȁ
- 作者：Konstantin G. Nazarenko ; Nataliya A. Shtil ; Sergey A. Buth ; Alex ; er N. Chernega ; Miron O. Lozinskii ; Andrey A. Tolmachev
- 关键词：Chloro derivatives ; Enamines ; Electrophilic substitution ; Spiro heterocycles ; Rearrangement
- 刊名：Tetrahedron
- 出版年：2008
- 期刊代码：107_00404020
- 类别：ch
- 出版时间：5 May 2008
- 卷：64
- 期：19
- 页码：4478-4485
- 文件大小：436 K
摘要
The reaction of 2-chloro-3-oxo-3,4-dihydro-2H-1,4-benzothiazines with ‘push–pull’ enamines was investigated. The reaction with the enamines occurs at the β-carbon atom in the presence of a small excess of triethylamine. As a result, a set of 3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl derivatives of 1,3-dicarbonyl compounds and benzothiazinone spiro derivatives was prepared. On acidic hydrolysis of ethyl 2-ethyl-3-(methylimino)-2-(3-oxo-3,4-dihydro-2H-1,4-benzothiazin-2-yl)butanoate, a new rearrangement affording ethyl 11-ethyl-2,3-dimethyl-4-oxo-2,3,4,5-tetrahydro-1H-2,5-methano-6,1,3-benzothiadiazocine-11-carboxylate was discovered. A plausible mechanism and factors influencing the course of the reaction are discussed.