Dichloromethane → (2R)-2-[(2S)-3-(Benzoylthio)-2-methylpropionylamino]-3-(4-methylbenzylthio)propionic acid

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Reaction Steps

Triethylamine (0.464 ml) is added to a solution of S-(4-methylbenzyl)-L-cysteine (reference compound No. 2-1, 500 mg) in a mixed solvent of methylene chloride (20 ml)/dimethylformamide (5 ml) under ice-cooling, and the mixture is stirred. 4-Nitrophenyl (2S)-3-benzoylthio-2-methylpropionate (reference compound No. 1-1, 919 mg) is added to the system of reaction, and the system is stirred overnight. The system of reaction is further stirred overnight at 40° to 50° C. After the reaction is completed, the mixture is concentrated under reduced pressure, a 10%, aqueous citric acid solution is added to the residue, and the whole is extracted with ethyl acetate. The organic layer is washed with water and a saturated sodium chloride solution successively, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue is purified by silica gel column chromatography to give 660 mg (68.9%) of the titled compound. (Compound No. 1-1)

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