Regioselective conversion of cycloalkanones to vinyl bromides with 1,2-functionality transposition. A general stratagem
作者:Leo A. Paquette、Karl Dahnke、Julien Doyon、Wei He、Kenetha Wyant、Dirk Friedrich
DOI:10.1021/jo00021a044
日期:1991.10
Cyclic beta-keto esters, available by regioselective acylation of cycloalkanone enolates, are rapidly transformed to alpha,beta-unsaturated acids. This functionality transposition allows the derived 3-hydroxy-4-methylthiazole-2-(3H)-thione derivatives to serve as precursors to synthetically useful vinyl bromides. The process involves heating the hydroxamate ester with AIBN in bromotrichloromethane solution. Alkylative and ring contractive variants of the methodology are highlighted. The short sequence makes available precursors to vinyl anions that are not otherwise conveniently accessible.