Synthesis of cyclobutane lignans via an organic single electron oxidant–electron relay system

Abstract

A direct method to synthesize lignan cyclobutanes and analogs <i>via</i> photoinduced electron transfer is presented. A variety of oxygenated alkenes are employed to furnish terminal or substituted cyclobutane adducts with complete regiocontrol, yielding cycloadducts with <i>trans</i> stereochemistry. Key to minimizing competing cycloreversion is the inclusion of an aromatic electron relay (ER). This method has been adapted to the synthesis of the natural products magnosalin and pellucidin A.