Iridium-catalyzed asymmetric hydrogenation of olefins using pyridine-phosphinites derived from the chiral pool

Abstract

Cationic iridium complexes containing chiral pyridine-phosphinites, with their chirality derived from menthol or mandelic acid, were assessed in hydrogenations of trisubstituted nonfunctionalized olefins. Complexes with the new ligands showed high reactivity towards most of the olefins tested. The enantioselectivities varied with the structures of the substrate and the ligand. Best results were obtained in the hydrogenation of 3-hydroxy-2-methyl-1- phenylpropene using a ligand prepared from (-)-menthol, pyridyllithium and diphenylchlorophosphine (>99% conversion, 92% ee). ©ARKAT USA, Inc.