Metal-free synthesis of phosphinoylchroman-4-ones via phosphinoylation/cyclization cascade mediated by K2S2O8

A variety of chroman-4-ones bearing phosphine oxide motifs were conveniently synthesized from readily available diphenylphosphine oxide and alkenyl aldehydes via a metal-free tandem phosphinoylation/cyclization protocol. The reaction utilizes K2S2O8 as oxidant and proceeds in DMSO-H2O at environmentally benign conditions with broad substrate scope and afforded the title compounds in moderate yields.