NEW MATERIAL: Compounds of formula I {wherein R1, R2 are H, a 1-6C alkyl [substituted with amino, a 1-6C alkylamino, (a 1-6C alkoxy-2-4C alkyl)amino, OH, a 1-3C alkylthio, a 1-3C alkylsulfonyl, morpholino, thiomorpholino, thiomorpholino-S-oxide, etc.]} or salts which can be used ophthalmologically or medicically.

EXAMPLE: 5-[N-(2,2,-Dimethylaminoethyl)carbamoyl]thieno[2,3-b]thiophene-2- sulfonamide.

USE: Drug. Carbonic anhydrase inhibitor for treatment of glaucoma and elevated intraocular pressure.

PROCESS: A compound of formula II is reacted with chlorosulfonic acid in the presence of PCl3 to prepare a compound of formula III, which is reacted with ammonium hydroxide to make a compound of formula IV. Next the compound is reacted with an amine in an alcohol solvent to obtain a compound of formula I.