Synthesis of chiral monodentate binaphthophosphepine ligands and their application in asymmetric hydrogenations

A general synthesis of chiral monodentate 4,5-dihydro-3H-dinaphthophosphepines 4 and a detailed study of the catalytic performance of the resulting ligands 4a-n in benchmark hydrogenation reactions is presented. Hydrogenation of methyl alpha-acetamidocinnamate 11 and methyl alpha-acetamidoacrylate 13 proceeded with enantioselectivities up to 95% and 94%, respectively. The best enantioselectivity for the rhodium-catalyzed hydrogenation of dimethyl itaconate 15 was 88%. (C) 2004 Elsevier Ltd. All rights reserved.