Photocatalytic Barbier reaction visible-lightinduced allylation and benzylation of aldehydesand ketones

摘要

We report a photocatalytic version of the Barbier type reaction using readily available allyl or benzylbromides and aromatic aldehydes or ketones as starting materials to generate allylic or benzylic alcohols.The reaction proceeds at room temperature under visible light irradiation with the organic dye 3,7-di(4-biphenyl)1-naphthalene-10-phenoxazine as a photocatalyst and DIPEA as sacrificial electron donor. Theproposed cross-coupling mechanism of a ketyl- and an allyl or benzyl radical is supported byspectroscopic investigations and cyclic voltammetry measurements.