Hydrochloric Acid → Methyl 4-(chlorosulfonyl)thiophene-3-carboxylate

Reaction equation

[Cl:1][S:2]([C:5]1[C:6]([C:10](Cl)=[O:11])=[CH:7][S:8][CH:9]=1)(=[O:4])=[O:3].[CH3:13][OH:14].Cl>C(Cl)(Cl)Cl>[CH3:13][O:14][C:10]([C:6]1[C:5]([S:2]([Cl:1])(=[O:4])=[O:3])=[CH:9][S:8][CH:7]=1)=[O:11]

Participants

Procedure

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.