Chiral diphosphites as ligands for the rhodium- and iridium-catalysed asymmetric hydrogenation: Precatalyst complexes, intermediates and kinetics of the reaction

Rh-I and Ir-I complexes [M(cod)PP]BF4 were synthesised from diphosphite lig ands PP with a backbone derived from xylofuranose. They were used in the rh odium- and iridium-catalysed asymmetric hydrogenation of itaconic acid, alp ha-acetamidocinnamic acid and methyl alpha-acetamidoacrylate. The kinetics of the reaction was investigated. The solution structures of the intermedia tes were studied by P-31- and H-1-HPNMR spectroscopy and a catalytic cycle is proposed.