Amino Imidate-Catalyzed Asymmetric Michael Reactions of Ketones and Nitroalkenes

The efficiency of an amino imidate organocatalyst was evaluated in the Michael reaction of ketones with nitroalkenes. tert-Butyl L-proline imidate was found to be a syn-selective catalyst generating products with moderate to good enantioselectivities, of up to 84% e.e. The best substrates were found to be cyclic ketones and -nitrostyrenes. The catalytic efficiency and enantioselectivity was enhanced by the addition of 10 mol% of benzoic acid.