Cobalt-Catalyzed Chemoselective Transfer Hydrogenation of C=C and C=O Bonds with Alkanols

An environmentally benign protocol of chemoselective transfer hydrogenation of C=C and C=O bonds with alkanols under base-free conditions is developed by this study, wherein the cobalt-bidentate phosphine catalyst precursor is commercially available and the active low-valent Co species could be generated in-situ. For the conjugation enones, the vinyl group is selectively reduced, whereas with nonconjugated alkenones, the selectivity is changed to the carbonyl group. Besides, orthoalkenyl-benzaldehydes/imines are well tolerated, and the reduction solely occurs at the C=O/C=N site with this protocol.