3-Thiophenecarboxylic acid, 4-(aminosulfonyl)-, methyl ester → thieno[3,4-d]isothiazol-3(2H)-one 1,1-dioxide

Participants

Reaction Steps

31.6 g (0.143 mole) of methyl 4-sulfamoylthiophene-3-carboxylate (IX; R1 =H; R=CH3) is refluxed for 20 hours in 150 ml of 1N methanolic sodium methylate solution. The methanol is evaporated, the residue taken up in water, and the aqueous phase extracted with methylene chloride and acidified with concentrated hydrochloric acid; the product precipitates as crystals. It may be recrystallized from water or ethanol.

Provenance & Evidence