Iridium-Catalyzed, Site-Selective Silylation of Secondary C(sp3)-H Bonds in Secondary Alcohols and Ketones.

We report the iridium-catalyzed, stereoselective conversion of secondary alcohols or ketones to anti-1,3-diols by the silylation of secondary C-H bonds γ to oxygen and oxidation of the resulting oxasilolane. The silylation of secondary C-H bonds in secondary silyl ethers derived from alcohols or ketones is enabled by a catalyst formed from a simple bisamidine ligand. The silylation occurs with high selectivity at a secondary C-H bond γ to oxygen over distal primary or proximal secondary C-H bonds. Initial mechanistic investigations suggest that the source of the newly achieved reactivity is a long catalyst lifetime resulting from the high binding constant of the strongly electron-donating bisamidine ligand.