Formation of styrene derivatives from dibromocarbene adducts of cyclohexa-1,4-dienes

Abstract

The bisdibromocarbene adduct (I; R¹= R²= OMe) from 1,4-dimethoxycyclohexa-1,4-diene, when heated in basic and in neutral media, gave 2,3′-dibromo-4′-methoxyacetophenone and 3′-bromo-4′-methoxyacetophenone. The diadduct (I; R¹= H, R²= OMe) from 1-methoxycyclohexa-1,4-diene in neutral medium gave the two isomeric 3,β-dibromo-4-methoxystyrenes (VIII; R¹= H), and 4′-bromo-3′-methoxyacetophenone, besides a small amount of 3-bromobenzoic acid. The adduct (I; R¹= R²= H) from cyclohexa-1,4-diene itself showed no significant reaction.