A Change from Kinetic to Thermodynamic Control Enables trans- Selective Stereochemical Editing of Vicinal Diols.

Here, we report the selective, catalytic isomerization of cis -1,2-diols to trans -diequatorial-1,2-diols. The method employs triphenylsilanethiol (Ph 3 SiSH) as a catalyst and proceeds under mild conditions in the presence of a photoredox catalyst and under blue light irradiation. The method is highly chemoselective, broadly functional group tolerant and provides concise access to trans -diol products which are not readily obtained using other methods. Mechanistic studies reveal that isomerization proceeds through a reversible hydrogen atom transfer pathway mediated by the silanethiol catalyst.