Ethyl iodoacetate → 3-(N-carbethoxymethyl-N-methylsulfamoyl)-thiophene-2-carboxylic acid methyl ester

참여 물질

반응 단계

43.5 G. (0.184 mol) of the obtained 3-methylsulfamoyl-thiophene-2-carboxylic acid methyl ester are dissolved in 400 ml. of absolute dimethylformamide are added dropwise at 0° C. during 1 hour to a stirred suspension of 4.5 g. (0.187 mol) of sodium hydride in 50 ml. of absolute dimethylformamide. Then, 40 g. (0.187 mol) of iodoacetic acid ethyl ester dissolved in 50 ml. of absolute dimethylformamide are added dropwise during 2 hours while cooling at 0°-5° C. and the mixture allowed to react for a further 1 hour [until a moistened pH paper shows a pH of 7-8]. The mixture is evaporated in vacuo and the residue taken up with 300 ml. of 0.5-N hydrochloric acid and 300 ml. of methylene chloride. The organic phase is separated, the aqueous phase is back-extracted twice with a small amount of methylene chloride and the combined organic phases are shaken out twice with 100 ml. each time of a 5% sodium bicarbonate solution [the aqueous phases are back-extracted once each time with a small amount of methylene chloride]. The combined organic phases are dried over sodium sulfate and evaporated. The crystalline residue is digested with a small amount of cold ethanol for purification. There is obtained 3-(N-carbethoxymethyl-N-methylsulfamoyl)-thiophene-2-carboxylic acid methyl ester of melting point 83°-85° C.

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