Benzylic C−H acylation by cooperative NHC and photoredox catalysis

Abstract

Methods that enable site selective acylation of sp³ C-H bonds in complex organic molecules are not well explored, particularly if compared with analogous transformations of aromatic and vinylic sp² C-H bonds. We report herein a direct acylation of benzylic C-H bonds by merging N-heterocyclic carbene (NHC) and photoredox catalysis. The method allows the preparation of a diverse range of benzylic ketones with good functional group tolerance under mild conditions. The reaction can be used to install acyl groups on highly functionalized natural product derived compounds and the C-H functionalization works with excellent site selectivity. The combination of NHC and photoredox catalysis offers options in preparing benzyl aryl ketones.

Direct acylation of sp3 C−H bonds in complex organic molecules is not well established compared to that of sp2 C−H bonds. Here, the authors report the combination of N-heterocyclic carbene (NHC) and photoredox catalysis for the direct and site-selective acylation of benzylic C−H bonds.