Energy Transfer Catalysis by Visible Light: Atrop‐ and Regio‐Selective Intermolecular [2+2]‐Photocycloaddition of Maleimide with Alkenes

Intermolecular [2+2]‐photocycloaddition of atropisomeric phenyl maleimide has been evaluated with substituted alkenes with complete control over regiochemistry. We were also successful in carrying out atropselective reactions with the removal of axial chirality leading to enantio‐enriched photoproducts. Based on detailed photophysical studies, a mechanistic rationale is proposed for the observed selectivity. Atrop‐ and regio‐selective intermolecular [2+2]‐photocycloaddition of maleimide with alkenes by energy transfer catalysis under visible light.