Benzisoselenazolones and process for the treatment of rheumatic and arthritic diseases using them

A benzisoselenazolone having the general formula I ##STR53## wherein R.sub.1 and R.sub.2 which may be the same or different from each other, represent hydrogen, fluorine, chlorine, bromine, C.sub.1 to 4 -alkyl, C.sub.1 to 4 -alkoxy, hydroxy, trifluoromethyl, nitro, or R.sub.1 and R.sub.2 together represent the methylenedioxy group --O--CH.sub.2 --O--, R.sub.3 and R.sub.4 which may be the same or different from each other, represent hydrogen, fluorine, chlorine, bromine, C.sub.1 to 4 -alkyl, C.sub.1 to 4 -alkoxy, hydroxy, trifluoromethyl, nitro, di-(C.sub.1 to 4 -alkyl)-amino or, R.sub.3 and R.sub.4 together, represent the methylenedioxy group --O--CH.sub.2 --O-- or R.sub.3 represents hydrogen with R.sub.4 being --CN, --COOR.sub.5 or ##STR54## wherein R.sub.5 is hydrogen, an alkali metal ion or C.sub.1 to 4 -alkyl and R.sub.6 being hydrogen, methyl or ethyl, and n is 0 or an integer from 1 to 4, with the exclusion of the compounds of formula I, wherein n is 0, R.sub.1, R.sub.2 and R.sub.3 are hydrogen and R.sub.4 is hydrogen or o-methyl or n is 1 and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are hydrogen.