Efficient synthesis of new 6-arylphenanthridines based on microwave-assisted Suzuki–Miyaura cross-coupling and Pictet–Spengler dehydrogenative cyclization in a zinc chloride/[Bmim]BF4 mixture

Abstract

An ecofriendly, efficient method for the synthesis of new pharmacologically active 6-arylphenanthridines has been developed for the first time. This method involves consecutive microwave-assisted Suzuki–Miyaura and Pictet–Spengler processes starting from inexpensive available 2-bromoaniline derivatives and 3,4-dimethoxyphenylboronic acid to be easily converted into 2-aminobiphenyl precursors, which react smoothly with diverse aromatic aldehydes to provide valuable polyfunctionalized 6-arylphenanthridines in moderate to excellent yields (45–98%) using a zinc chloride/[Bmim]BF₄ mixture as both a useful catalytic system and reaction medium.