Ethanol → Ethyl 2-amino-4,5,6,7-tetrahydro-1,3-benzothiazole-6-carboxylate hydrobromide

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反応条件

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A 3 liter reactor equipped with mechanical stirrer, thermometer and condenser was loaded with 1500 ml of ethanol and 200 g of 4-oxo-cyclohexanecarboxylic acid ethyl ester. After cooling to 0° C., 188 g of bromine were dropped therein in about 1 hour. The temperature was raised to 10° C., then to the room one after discolouration. After 1 hour, 89.32 g of thiourea were added in portions to obtain a suspension, that was refluxed to obtain gradual dissolution of the solid. After 4 hours the solution was concentrated to small volume to obtain a solid mass, that was suspended in 800 ml of acetone and refluxed to obtain a solution. The solution was then cooled to room temperature to precipitate a solid, then to 0° C. and after 4 hours the solid was filtered, washed twice with 100 ml of cold acetone and dried to obtain 170 g of the title product.

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