摘要:
New electron-rich chiral 1,3-diphosphines of the BDPP type were prepared from 1, 3-diphenylpropane- 1,3-diol by an economically feasible synthetic approach. The a-donor properties of the phosphines were determined by measurement of J(P-31-Se-77) coupling constants in the corresponding phosphine selenides. For comparison related, but electronically different, 1,3-diphosphines were considered. The new diphosphines showed good enantioselectivities as ligands in the Rh-catalyzed enantioselective hydrogenation of benchmark substrates and beta-amino acid precursors (up to 98% ee). The electronic effects on the outcome of the enantioselective catalysis have been analyzed. (c) 2005 Published by Elsevier Ltd.