[CH3:1][O:2][C:3](=[O:8])[CH:4](Cl)[CH:5]=O.[NH2:9][C:10]([NH2:12])=[S:11].C>O>[CH3:1][O:2][C:3]([C:4]1[S:11][C:10]([NH2:12])=[N:9][CH:5]=1)=[O:8]A mixture of 2.4 g of 2-chloro-3-oxo-propionic acid methyl ester (8-2), water 20 ml and 1.75 g of thiourea was refluxed for 2 hours. The mixture was cooled to room temperature and 0.25 g of norit was added and filtered. A solution of 2.5N sodium hydroxide was added to the filtrate until neutral pH. The filtration yielded 1.23 g (44%) of 2-amino-thiazole-5-carboxylic acid methyl ester (8-3).
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