A convenient method for the α-alkylation of (S)-asparagine with “self-regeneration of the stereogenic
center” is described. The synthetic protocol involves stereoselective conversion of (S)-asparagine
into enantiopure imino ether (2S,6S)-9, which is then alkylated with complete diastereoselectivity
to give trans products 10−13 in good yields. Hydrolysis of these alkylated heterocycles is
accomplished under mild acidic conditions to give the desired, enantiopure α-alkyl aspartic acids
in excellent yields.