Iridium-catalyzed diborylation of benzylic C–H bonds directed by a hydrosilyl group: synthesis of 1,1-benzyldiboronate esters

We describe a regioselective diborylation of primary benzylic C-H bonds catalyzed by [Ir(COD)OMe](2) and 4,4'-di-tert-butyl-2,2'-bipyridine (dtbpy). The hydrosilyl group acts as a traceless directing group, providing access to a range of 1,1-benzyldiboronate esters in good yields. Transformations of the 1,1-benzyldiboronate ester products include chemoselective Suzuki-Miyaura cross-couplings and synthesis of tetrasubstituted alkenyl boronate esters.