Green Metal-Free Photochemical Hydroacylation of Unactivated Olefins.

Direct alkylation of C(sp2 )-H bonds to convert an aldehyde into a ketone is a notorious transformation, due to the laborious challenge of the formation of ketyl or acyl radicals. Herein, we report a green, cheap, metal-free and efficient method for the hydroacylation of olefins in water. This photochemical protocol utilizes phenylglyoxylic acid, a commercially available small organic molecule, as the photoinitiator, water as the solvent and household fluorescent lamps as the irradiation source, leading to a broad substrate scope of products in moderate to good yields. A wide range of aromatic and aliphatic aldehydes, terminal and non-terminal alkenes and pharmaceutically relevant molecules can be employed, without the need of directing groups and additives or metal catalysts.