Efficient enantioselective synthetic methods for ( R)-α-alkylhomoserines and ( R)-α-alkylhomocysteines havebeen developed. The phase-transfer catalytic alkylation of 2-phenyl-5,6-di-hydro-4 H-1,3-oxazine-4-carboxylic acid TERT-butyl ester and 2-phenyl-5,6-dihydro-4 H-1,3-thiazine-4-carboxylic acid TERT-butyl ester, in the presence of N-2′,3′,4′-trifluorobenzylcinchonidinium bromide,gave the corresponding