反应详情

44.1 G. (0.18 mol) of the obtained 4-chlorosulfonylthiophene-3-carboxylic acid chloride are dissolved in 450 ml. of absolute chloroform, 9.6 g. (0.3 mol) of absolute methanol are added and the solution is heated to reflux for 9 hours [until termination of the hydrogen chloride evolution]. The mixture is then evaporated to dryness in vacuo, the residue crystallizing out. There is obtained 4-chlorosulfonylthiophene-3-carboxylic acid methyl ester, which can be converted into the 4-hydroxy-2-methyl-N-(2-thiazolyl)-2H-thieno[3,4-e]-1,2-thiazine-3-carboxamide 1,1-dioxide in a manner analogous to that described in the last four paragraphs of Example 5.

1. temperaturethe solution is heated
2. customThe mixture is then evaporated to dryness in vacuo
3. customthe residue crystallizing out