o-Quinone methides. Part 3. X-Ray crystal structure and reactivity of a stable o-quinone methide in the E-configuration

Abstract

An X-ray crystal structure determination of 6-(4-methoxybenzylidene)-3,4-methylenedioxycyclohexa-2,4-dienone (2a), allows an E-configuration to be assigned to this stable o-quinone methide. The reactions of (2a) with magnesium phenolates and ethyl vinyl ethers show the same pathway previously observed with unstable o-quinone methides, indirectly confirming the generally preferred E-configuration for these intermediates.