Preparation of optically pure α-trifluoromethyl-α-amino acids from N-tosyl-2-trifluoromethyl-2-alkyloxycarbonyl aziridine.

The preparation of optically pure α-trifluoromethyl-α-amino acids from N-tosyl-2-trifluoromethyl-2-alkyloxycarbonylaziridine is described. Optically pure aziridine was prepared with a 60% yield via three steps from optically pure 2,3-epoxy-1,1,1-trifluoropropane (TFPO). Ring-opening reactions of the aziridine with a variety of nucleophiles and subsequent deprotection of the N-tosyl moieties gave the optically pure β-substituted-α-trifluoromethyl-α-amino acids in moderate to good yields (up to 85%) without racemization at the quaternary stereogenic center of the amino acid.