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

A micellar enlarged Rh-(2S,4S)-N-tert-butoxycarbonyl-4-diphenylphosphino-2- diphenyl-phosphino-methyl-pyrrolidine (BPPM) catalyst was used for the enan tioselective hydrogenation of ol-amino acid precursors in a membrane reacto r, equipped with an ultrafiltration membrane. The chiral a-amino acid deriv atives were obtained with good enantioselectivity and space-time yields. Th e catalyst, embedded in micelles, obtained from triblock copolymers as surf actants, was retained and reused several times without loss of activity and enantioselectivity. Only a minimal leaching of the catalyst components was found. (C) 2001 Elsevier Science B.V. All rights reserved.