A boron-catalyzed α-allylation of carboxylic acids with allylsulfones under blue LED irradiation conditions is developed. We propose that photoexcitation of catalytically generated boron enediolates induces single-electron transfer to the allylsulfones. Subsequent C−C bond formation through a radical reaction constructs sterically demanding quaternary carbon centers at the position α to the carboxy group. The π-extended ligand on the boron atom is likely the key for efficient photoexcitation of the boron enediolates.

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