Studies on Optically Active Amino Acids. XV. Studies on α-Alkyl-α-amino Acids. VIII. Absolute Configuration of Optically Active α-Methylserine and 2-Amino-2-methyl-3-butenoic Acid.

The absolute configuration of (+)-α-methylserine ((+)-IX) obtained from natural source, has been elucidated to be S-configuration by the chemical correlation with (+)-isovaline ((+)-VII), at the same time the absolute configuration of (+)-2-amino-2-methyl-3-butenoic acid ((+)-XI) has also been proved to be S-series. Chemical schemes employed were shown in Charts 1 and 2. Optically active hydantoins (V and VIII) used in the correlation were prepared by the direct resolution of racemic hydantoins with brucine. Preliminary examinations using racemic compounds were also reported.