HCID 16679760、化合物 → HCID 16679762、化合物

N-carbamoyl-S-tert-butyl-α-methyl-L-cysteine (82.4 g, 351.4 mmol) was dissolved in a 18% aqueous lithium hydroxide solution (630 g), and the resultant solution was refluxed in nitrogen for 41 hours. After the solution was allowed to cool down to room temperature, the insoluble substance was filtered off, and the filtrate was adjusted to pH 6 by adding conc. hydrochloric acid (180.1 g). After stirring for about 1 hour, the mixture was cooled to 4° C. to 5° C., and further stirred for 1 hour. The produced crystals were filtered off, washed with water, and then dried under reduced pressure to obtain the title compound as a white solid (53.9 g). As a result of HPLC analysis (column: COSMOSIL 5C18-AR (produced by Nacalai Tesque Inc.), mobile phase: potassium dihydrogen phosphate-phosphoric acid solution (pH 2.0)/acetonitrile=90/10, flow rate: 1.0 ml/min, detection wavelength: 210 nm, column temperature: 40° C.), it was confirmed that the solid was the desired compound (yield 85.7%)