the process for obtaining 4 -- 5 , 6 - dihydro - 4h - thien -- thiopyran - 2 - sulfonamide - 7 , 7 - dioxides wherein r 1 is h or c 1 - 5 alkyl , and r 2 is c 1 - 5 alkyl , starts from the corresponding 4 -- 5 , 6 - dihydro - 4h - thien -- thiopyran - 7 , 7 - dioxides , and comprises protecting the alkylamine group , introducing a sulfonamide group and eliminating protecting group . some compounds of formula are inhibitors of the carbonic anhydrase and can be used in the treatment of elevated intraocular pressure