Trichloromethylative Olefin Lactonization by Photoredox Catalysis

A trichloromethylative olefin lactonization reaction using an iridium photoredox catalyst was developed. The reactions proceeded at room temperature for olefins with various substituents and substitution patterns, and a variety of lactones with a tetrasubstituted carbon and trichloromethyl group were obtained regio- and stereoselectively. The reaction mechanism was elucidated through isotope labeling experiments. The chemical properties of the lactones containing the trichloromethyl groups were investigated, and synthetic transformations of the product were realized. Trichloromethylative olefin lactonization was reported. A photoredox iridium catalyst irradiated with blue LEDs promoted the reaction without using hazardous reagents. The mechanistic studies were performed by experimental and theoretical means. The trichloromethyl moiety of the product could be converted to the corresponding dichloroalkene and chloroalkyne in addition to the carboxyl group.image