摘要:
Derivatives of para- and meta-phenylene bis-alanine and related biphenyl systems, carrying four orthogonal protecting groups, were synthesised via combinations of Heck couplings and asymmetric hydrogenations, The intermediate unsaturated arylalanine derivatives were hydrogenated using [Rh(COD)((R,R)-DIPAMP)]+BF4- or [Rh(COD)(Me-DuPHOS)]X-+(-) as catalysts to produce the optically active, protected amino acid derivatives in greater than or equal to 98% e.e. as analysed by chiral phase HPLC. (C) 1998 Elsevier Science Ltd. All rights reserved.