Highly enantioselective transfer hydrogenation catalyzed by diasteromeric mixtures of axially chiral (aR,S)- and (aS,S)-Biscarbolines

The mixtures of axially chiral (aR,S)- and (aS,S)-biscarboline alcohols were firstly used as catalysts in enantioselective 1,2- and 1,4-transfer hydrogenations of ketimines and β-enamino esters, respectively. This mixed axially chiral catalysts exhibited excellent enantioselectivity (up to 98%ee) in the transfer hydrogenations under mild reaction conditions. [Display omitted] •The mixtures of axially (aR,S)- and (aS,S)-biscarbolines exhibited excellent enantioselectivity in transfer hydrogenations.