The recently introduced concept of Frustrated Lewis Pairs (FLPs) opened a way for efficient metal free hydrogenation catalysis. The variety of FLP-based catalysts is rapidly increasing; the reported catalytic systems are nowadays able, in high yields and selectivity, to hydrogenate a vast range of unsaturated substrates: imines, enamines, enol esters, heterocycles, etc. However, despite all efforts made, it is still problematic to provide highly enantioselective hydrogenation of unsaturated compounds with the use of FLP-based catalysts. To present day, there are only few studies presented, that discuss this highly actual topic.In the actual work, a new chiral FLP-based catalytic system is presented. A chiral binaphtyl amino-borane catalyst for asymmetric hydrogenation of imines and enamines was prepared via a short synthetic sequence from commercially available starting materials. The synthesis of the amino-borane was carried out to retain the original enantiopurity of the chiral precursors. Activation of hydrogen with the system occurred rapidly and was readily reversible. The obtained zwitterionic catalyst hydrogenated a wide range of imines and enamines at mild conditions in high yields and enantioselectivity (with ee's up to 95 %).

Catalytic asymmetric hydrogenation of imines and enamines with a binaphtyl amino-borane FLP

248th National Meeting (2014)

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