[2 + 2]-Photocycloaddition of N-vinylcarbazole to dimethyl fumarate

Abstract

The [2 + 2]-photocycloaddition of photoexcited N-vinylcarbazole (VCZ) with dimethyl fumarate (F) in nonpolar benzene solvent yields an oxetane. This oxetane is subsequently cleaved to give two methoxydiene isomer products. The existence of the exciplex emission, the effect of solvent polarity on the photoproducts, and triplet sensitizer and quencher experiments prove the existence of a singlet exciplex intermediate in the photocycloaddition of VCZ and F.