Organocatalytic mannich-type reactions of trifluoroethyl thioesters.

Direct organocatalytic Mannich-type reactions of thioesters provide for the expedient and diastereoselective synthesis of protected beta-amino acids. A variety of thioesters were found to be reactive with different imines under mild conditions to provide beta-amino acids in good yields. This chemistry was extended to a diastereo- and enantioselective variant.