Catalytic Allylation Coupling between Equimolar Aldehydes and Alkenes via sp3 C‒H Activation

We here report a catalytic allylation of aldehydes with alkenes under equimolar conditions and visible-light irradiation. The reaction is enabled by an ion-pair electron donor–acceptor complex catalyst formed from a triphenylsilyl-substituted thiophosphoric imide (TPI) and 4-methylquinoline, in combination with a chromium chloride catalyst and a boroxine additive. This catalytic system accelerates the generation of a TPI-derived thiyl radical hydrogen atom transfer (HAT) catalyst, suppresses product-derived HAT, and enables equimolar coupling between diverse aldehydes and alkenes, including functionalized substrates. This strategy provides a preactivation-free platform for C–C bond formation from sp³ C–H-containing alkenes.