The Stereoisomers of 5-Bromo-6,8-dimethoxy-1,2,3-trimethyl-1,2,3,4-tetrahydroisoquinoline. X-Ray Crystal-Structure of the trans Isomer

Abstract

Henry reaction between 3,5-dimethoxybenzaldehyde (2) and nitroethane gave (E)-2-(3,5-dimethoxyphenyl)-1-methyl-1-nitroethene (3). Under mild conditions the erythro and threo nitro aldols intermediate in this reaction could be isolated as their acetates. The threo isomer was obtained in diastereoisomeric excess. The nitrostyrene (3) was converted in several steps into cis-(20) and trans-5-bromo-6,8-dimethoxy-1,2,3-trimethyl-1,2,3,4-tetrahydroisoquinoline (18). The single-crystal X-ray structure of compound (18) is reported.