Chiral Induction by Cinchona Alkaloids in the Rhodium(II) Catalyzed O-H Insertion Reaction

Cinchona alkaloids are effective additives for enantioselective O-H insertion of alpha-phenyldiazoacetate and water by rhodium(II) complexes. Addition of silica gel promotes O-H insertion in the reaction rate and the reaction proceeds smoothly at less than the freezing point of water, e.g., -10 degrees C, and provided mandelate in up to 50% ee. The results reported here are the highest asymmetric inductions obtained to date for O-H insertions via a Rh-carbenoid.