Asymmetric synthesis of homoproline derivatives via Rh(I)catalyzed hydrogenation using chiral bisphosphines as ligands

Abstract

It has been demonstrated for the first time that Rh(I)-catalyzed asymmetric hydrogenation of cyclic beta-enamino acid derivatives I using chiral bisphosphines could be a highly efficient synthetic method for optically active homoproline derivatives. The enantioselectivity and conversion yield were largely dependent upon the chiral ligand. Using the Me-BDPMI forming a seven-membered metal chelate, the N-acetylated beta-enamino acid methyl ester la was hydrogenated to give optically active homoproline derivative 2a with 100% conversion and 96% ee. (C) 2004 Elsevier Ltd. All rights reserved.