Novel bis (1,3,2-diazaphospholidine) ligands for asymmetric catalysis

Abstract

A family of modularly designed chiral bis(1,3,2-diazaphospholidines) with N-aryl substituents (NP-PN) is reported. These compounds have been prepared in two steps from readily available (R,R)-1,2-diaminocyclohexane and tetrachlorodiphosphines. Examples in the set differ in the backbone and the aryl substituents, aiming at their application in asymmetric catalysis. Thus, [Rh(NBD)(NP-PN)]BF4 complexes lead to active catalysts in the hydrogenation of methyl α-acetamidoacrylate, which provide enantioselectivities up to 96% ee. In addition, NP-PN ligands also generate active catalysts in the hydroformylation of vinyl acetate, leading to high regioselectivities (iso:n ratio higher than 99:1) and enantioselectivities up to 65% ee. © 2013 American Chemical Society.