[CH:1]1(N=C=NC2CCCCC2)CCCCC1.[O:16]=[C:17]1[S:21][CH2:20][CH:19]([C:22]([OH:24])=[O:23])[CH2:18]1.CO>C(OCC)C.CN(C1C=CC=CN=1)C>[CH3:1][O:23][C:22]([CH:19]1[CH2:18][C:17](=[O:16])[S:21][CH2:20]1)=[O:24]225 g (1.09 mol) of dicyclohexylcarbodiimide (DCC) are added in portions, while cooling with ice, to a solution of 160 g (1.095 mol) of tetrahydro-5-oxo-3-thiophenecarboxylic acid, 70 g (2.19 mol) of methanol and 4 g (32.8 mmol) of dimethylaminopyridine (DMAP) in 2.5 litres of diethyl ether. After 4 hours' stirring at room temperature, the dicyclohexylurea is filtered off and the filtrate is extracted with 500 ml of 2N hydrochloric acid and 500 ml of saturated sodium hydrogen carbonate solution, is washed with water and is dried over sodium sulfate. There are obtained 149 g of solid product having a melting point of 33°-35° C.
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