Iridium-catalyzed asymmetric hydrogenation of 2-substituted 1,4-benzodioxines

An Ir-catalyzed asymmetric hydrogenation of 2-substituted 1,4-benzodioxines was developed for the preparation of chiral 1,4-benzodioxanes, which are present in numerous biologically active compounds and natural products. Our tropos biphenyl phosphine-oxazoline ligand is essential for obtaining good ee. A broad range of substrates were tolerable to the reaction conditions and gave the corresponding hydrogenation products in excellent yields and with moderate to good enantioselectivities using the lr-complex of our tropos phosphine-oxazoline ligand. (C) 2017 Elsevier Ltd. All rights reserved.