Enantioselective Hydrogenation of Olefins Enhanced by Metal-Organic Framework Additives

The use of nonprotic solvents (e. g., dichloromethane, toluene) increases the enantioselectivity of the asymmetric hydrogenation of olefins with chiral [Rh(Me-BPE)(cod)] OTf [Me-BPE=1,2-bis(2,5-dimethylphospholano) ethane; cod=1,5-cyclooctadiene; OTf=triflate]. Readily available achiral metal-organic frameworks (MOFs) as additives yielded substantially enhanced reactivity. In toluene (but not dichloromethane), the MOFs adsorbed the homogeneous catalyst, which directly reduced rhodium contamination in the products of the reaction. The in situ formed heterogeneous catalyst was reused without loss in selectivity.