A Novel Heterobimetallic Asymmetric Hydrogenation Catalyst Based Upon a Chiral Rhenium Template Containing Two Phosphido Substituents

The Rhodium–rhenium complex 1 can be regarded as prototype of a new generation of hydrogenation catalysts. A salient-characteristic is the coupling of an Rh1 center—known to exhibit catalytic activity in hydrogenations—with a bis(diphenylphosphido) ligand, which contains a pseudo-tetrahedrally coordinated stereogenic Re atom in the skeletal framework. For example, α-acetamidoacrylic acid is hydrogenated in presence of 1 (0.4 mol-% in THF) with 1 atm H2 at room temperature to (R)-N-acetylalanine with 98% ee (yield: 82%).