Some studies involving the use of chiral amine oxides for the enantioselective preparation of (propargyl alcohol)Co₂(CO)₅(PR₃) complexes

The enantioselective preparation of (propargyl alcohol) dicobalt pentacarbonylphosphine complexes (2) via kinetic resolution with an optically active amine oxide was examined. Variations in temperature, solvent, phosphine, amine oxide, and substrate were studied. Diastereoselectivity showed marked improvement over thermal methods, while enantioselectivity was modest. The typical e.e. for product 2a was 20% at 30-40% conversion when the reaction was carried out at -58°C in a 1:1 mixture of tetrahydrofuran/dichloromethane with brucine N-oxide as the promoter.