Catalyst-free [4 + 2] cyclization of para-quinone methide derivatives with homophthalic anhydrides

Abstract

The title reaction has been established, which offers a useful method for the construction of dihydrocoumarin frameworks in generally good chemical yields (up to 99%) and high diastereoselectivities (up to >95 : 5 dr). This reaction represents a good example of [4 + 2] cyclizations of para-quinone methide derivatives with electron-rich reaction partners under catalyst-free conditions.