Asymmetric hydrogenation in a membrane reactor: recycling of the chiral catalyst by using a retainable micellar system

Abstract

A micellar enlarged Rh-(2 S,4 S)- N- tert-butoxycarbonyl-4-diphenylphosphino-2-diphenyl-phosphino-methyl-pyrrolidine (BPPM) catalyst was used for the enantioselective hydrogenation of α-amino acid precursors in a membrane reactor, equipped with an ultrafiltration membrane. The chiral α-amino acid derivatives were obtained with good enantioselectivity and space–time yields. The catalyst, embedded in micelles, obtained from triblock copolymers as surfactants, was retained and reused several times without loss of activity and enantioselectivity. Only a minimal leaching of the catalyst components was found.