Rhodium-catalysed hydrogenation of enamides with monodentate phosphorous ligands. A density functional theory study

The hydrogenation of enamides catalysed by rhodium complexes of monodentate phosphorous ligands has been studied by density functional theory. The role of trans intermediates, made accessible by the non-chelating nature of the ligand, has been taken into account. The findings here reported show that cis intermediates play the major role in the mechanism of the reaction, suggesting that data obtained with chiral monodentate phosphorous ligands or with a mixture of them should be interpreted excluding the intervention of structures with trans phosphine arrangement. Thus, results observed with monodentate phosphorous ligands must be interpreted in the light of the exclusive intervention of cis intermediates, without involvement of structures with trans phosphine arrangements. Copyright (C) 2010 John Wiley & Sons, Ltd.