Copper-catalyzed asymmetric addition of Et2Zn to 2-cyclohexen-1-one and 2-carbamoyloxy-2-cyclohexen-1-one with phosphoramidite, phosphite, and bidentate phosphite-oxazoline ligands

New biphenol-backboned phosphite-oxazoline bidentate ligands were synthesized and applied in the copper-catalyzed asymmetric conjugate additions on 2-cyclohexen-1-one with Et2Zn. In these reactions, the non-chiral oxazoline unit has demonstrated significant impact on the enantioselectivity. 2-Carbamoyloxy-2-cyclohexen-1-one is a new alpha-oxygenated cyclic enone substrate and was synthesized and applied to the aforementioned addition with certain phosphoramidite, phosphite, and the new bidentate ligands. Good ee has been obtained on this substrate. (C) 2009 Elsevier Ltd. All rights reserved.