Catalyst-Free Dichlorination of Alkenes by Direct Photoexcitation of N-Chloro(fluorenone imine)

A catalyst-free visible-light-induced dichlorination of alkenes has been developed using an N-chloro(fluorenone imine) reagent. The reaction proceeds through direct photoexcitation of the reagent under blue-light irradiation and enables vicinal dichlorination of aliphatic alkenes under mild conditions. Unprotected hydroxy and amino groups were tolerated, and comparable reactivity was observed under air. EPR analysis supported photoinduced N-Cl bond homolysis and was consistent with iminyl radical formation.