| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject compound having high optical purity by evaporating a film of a crude product obtained by reacting an optically active amino acid ester salt with phosgene in an organic solvent at a temperature below a specific temperature. SOLUTION: This optically active amino acid ester salt is obtained by evaporating a film of a crude optically active N-carbonylamino acid ester obtained by reacting an optically active amino acid ester salt (amino acid ester is preferably has an aromatic ring, e.g. methyl ester or ethyl ester of phenylalanine or S-phenylcysteine is exemplified and a chloride, etc., is exemplified as a salt) with phosgene in an organic solvent (e.g. an aromatic compound such as toluene or xylene, a halide such as chloroform, an acetic ester such as methyl acetate) below 100 deg.C (preferably 60-95 deg.C). Preferably, a film temperature in the film evaporation is 100-200 deg.C and the inner pressure is 20-100 mmHg. |
