Stereoarrayed CF3-Substituted 1,3-Diols by Dynamic Kinetic Resolution: Ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation

CF3-substituted 1,3-diols were stereoselectively prepared in excellent enantiopurity and high yield from CF3-substituted diketones by using an ansa-ruthenium(II)-catalyzed asymmetric transfer hydrogenation in formic acid/triethylamine. The intermediate mono-reduced alcohol was also obtained in very high enantiopurity by applying milder reaction conditions. In particular, CF3C(O)-substituted benzofused cyclic ketones underwent either a single or a double dynamic kinetic resolution during their reduction.