Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

摘要

In order to prepare asymmetrically ( R )-(+)-1-(5-bromopentyl)-1-methyl-7-methoxy-2-tetralone ( 3a ), a key intermediate of dezocine, 17 cinchona alkaloid-derived catalysts were prepared and screened for the enantioselective alkylation of 1-methyl-7-methoxy-2-tetralone with 1,5-dibromopentane, and the best catalyst ( C7 ) was identified. In addition, optimizations of the alkylation were carried out so that the process became practical and effective.