Ethyl Acetate → 2-(2-aminothiazol-4-yl)thioacetic acid-S-ethyl ester

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Reaction Steps

In 7.0 ml of N,N-dimethylacetamide was dissolved 2.25 g of the 4-bromo-3-oxothiobutyric acid-S-ethyl ester obtained in Referential Example 4-(1), and 1.14 g of thiourea was added to the resulting solution with ice-cooling, after which the resulting mixture was subjected to reaction at room temperature for 1 hour. The reaction mixture was introduced into a mixed solvent of 50 ml of ethyl acetate and 50 ml of water, and the pH was adjusted to 6.0 with sodium hydrogencarbonate. Then, the organic layer was separated, washed with two 50-ml portions of water and with 50 ml of saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate. Then the solvent was removed by distillation under reduced pressure. The residue obtained was recrystallized from 20 ml of ethyl acetate to obtain 1.32 g (yield, 65.5%) of 2-(2-aminothiazol-4-yl)thioacetic acid-S-ethyl ester having a melting point of 76°-77° C.

Provenance & Evidence