One-Pot Decarbonylative Borylation of Aliphatic Aldehydes

We present a mild and direct method for the radical borylation of simple aliphatic aldehydes. By employing an enamine and a photocatalyst under light irradiation, aldehydes can be transformed effectively into alkyl boronic esters via a formal decarbonylative process. This alternative route for radical borylation synthesis can not only be applied to the transformation of primary, secondary, and tertiary aldehydes but also be adapted to other radical conversion reactions through the generated alkyl radical intermediate. Mechanistic studies indicate that 4-alkyl-1,4-dihydropyridines, formed in situ from the aldehyde and enamine, are the key intermediate for the borylation process.