Stepwise photosensitized C(sp3)–C(CO) bond cleavage and C–P bond formation of 1,3-dicarbonyls with arylphosphine oxides

Abstract

A visible-light-induced metal-free cascade radical reaction of diarylphosphine oxides and 1,3-dicarbonyls was discovered to obtain β-ketophosphine oxides in moderate to excellent yields. On the basis of control experiments, cyclic voltammetry and Stern–Volmer quenching experiments, the target products were afforded via a cascade radical reaction of chemoselective C–C bond cleavage with a C–P bond formation. The active intermediates of PhCOO˙, β-dicarbonyl radical and P-radical were formed by the photosensitization process with single electron transfer (SET) or the free radical chain reaction with the decomposition of BPO under visible light irradiation. The obtained β-ketophosphine oxides could serve as good ligands to sensitize the Eu(III) metal centre.