Use of rhodium complexes with amphiphilic and nonamphiphilic ligands for the preparation of chiral α-aminophosphonic acid esters by hydrogenation in micellar media
Several kinds of micelle forming amphiphiles were tested in the asymmetric hydrogenation of the prochiral dialkyl 1-benzamido-2-phenyl-ethenephosphonates in aqueous media. The chiral catalytic system [Rh(cod)(2)]BF4/BPPM or amphiphilized PPM proved to be suitable for the hydrogenation reaction affording enantiomeric excesses up to 99%. A chiral induction is possible to a certain extent (up to 11% ee) by selected chiral amphiphiles in the presence of achiral rhodium catalysts. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.