Photo-hydroacylation: 1-tetralones from ortho-allylbenzaldehydes

A light-induced intramolecular hydroacylation of ortho-allylbenzaldehydes is presented, yielding the selective formation of a six-membered ring in 1-tetralones. The photo-hydroacylation proceeds at 365 nm, ambient temperature, and additive-free conditions. The proposed mechanistic pathway involves a light-induced 1,5-hydrogen atom transfer (1,5-HAT) and a radical recombination process leading to the formation of the 1-tetralone product. Deuteration and radical-clock experiments support the mechanism. This efficient photo-hydroacylation provides a valuable method for the synthesis of various tetralone scaffolds through light activation.