Cobalt-Catalyzed Chemo- and Enantioselective Hydrogenation of Conjugated Enynes

Asymmetric hydrogenation is one of the most powerful methods for the preparation of single enantiomer compounds. However, the chemo- and enantioselective hydrogenation of the relatively inert unsaturated group in substrates possessing multiple unsaturated bonds remains a challenge. We herein report a protocol for the highly chemo- and enantioselective hydrogenation of conjugated enynes while keeping the alkynyl bond intact. Mechanism studies indicate that the accompanying Zn2+ generated from zinc reduction of the Co-II complex plays a critical role to initiate a plausible Co-I/Co-III catalytic cycle. This approach allows for the highly efficient generation of chiral propargylamines (up to 99.9% ee and 2000 S/C) and further useful chemical transformations.

Automated summary

Asymmetric hydrogenation is an effective method for preparing single enantiomer compounds, but the chemoselective and enantioselective hydrogenation of relatively inert unsaturated groups in substrates with multiple unsaturated bonds remains a challenge. A highly selective hydrogenation method for producing chiral propargylamines and enabling useful chemical transformations has been reported.