Rhodium-catalyzed asymmetric hydrogenations of electron deficient olefins using 1,4-diphosphine ligands bearing an imidazolidin-2-one backbone

Abstract

In rhodium(1)-catalyzed asymmetric hydrogenations of electron deficient olefins, the electron-rich and sterically encumbered phosphine ligand, MOD-BDPMI, exhibited higher enantioselectivities than BDPMI ligands. Moreover, the N-substituents of the imidazolidin-2-one backbone affected the enantioselectivity. Thus, using the N,N'-dimethylated MOD-BDPMI ligand 2b, (Z)-alpha-(N-acetamido)cinnamic acid 3 was hydrogenated with 100% conversion to give the saturated a-amino acid with ee of 88.7%. (C) 2002 Elsevier Science Ltd. All rights reserved.