Pyridine-boryl radical-mediated reductive homocoupling of para-quinone methides

Abstract

An effective and straightforward pyridine-boryl radical-mediated reductive homocoupling of para-quinone methides was developed, affording a broad range of differently substituted tetraarylethane derivatives in good to nearly quantitative yields. This metal-free procedure is characterized by operational simplicity, ready availability of starting materials, high atom economy and a broad substrate scope under mild reaction conditions. Moreover, the products were easily further transformed into valuable tetraphenylethylenes, possessing aggregation-induced emission (AIE) behaviour. Additionally, gram-scale reactions and control experiments were also studied.