Abstract: A compound of the formula Het--NR--SO.sub.2 --Ph.sup.2 --A--Ph.sup.1 (COOH)(OH) and tautomic form, salts, solvates, C.sub.1-6 alkyl esters and pharmaceutical compositions of the compound. Ph.sup.1 and Ph.sup.2 are benzene rings with the proviso that carboxy and hydroxy are ortho to one another. Het includes an optionally substituted heterocyclic ring which includes conjugated double bonds and binds to nitrogen in NR. The compound is characterized in that A is a bridge which is stable against reduction because it is not azo, and in that R is hydrogen or lower alkyl.The invention also includes the preparation of the compound and its use as a drug, particularly for treating autoimmune diseases.

Abstract: A compound of the formula Het--NR--SO.sub.2 --Ph.sup.2 --A--Ph.sup.1 (COOH)(OH) and tautomic form, salts, solvates, C.sub.1-6 alkyl esters and pharmaceutical compositions of the compound. Ph.sup.1 and Ph.sup.2 are benzene rings with the proviso that carboxy and hydroxy are ortho to one another. Het includes an optionally substituted heterocyclic ring which includes conjugated double bonds and binds to nitrogen in NR. The compound is characterized in that A is a bridge which is stable against reduction because it is not azo, and in that R is hydrogen or lower alkyl.The invention also includes the preparation of the compound and its use as a drug, particularly for treating autoimmune diseases.

Abstract: A compound of the formula Het--NR--SO.sub.2 --Ph.sup.2 --A--Ph.sup.1 (COOH)(OH) and tautomeric form, salts, solvates, C.sub.1-6 alkyl esters and pharmaceutical compositions of the compound. Ph.sup.1 and Ph.sup.2 are benzene rings with the proviso that carboxy and hydroxy are ortho to one another. Het includes an optionally substituted heterocyclic ring which includes conjugated double bonds and binds to nitrogen in NR. The compound is characterized in that A is a bridge which is stable against reduction because it is not azo, and in that R is hydrogen or lower alkyl.The invention also includes the preparation of the compound and its use as a drug, particularly for treating autoimmune diseases.

Abstract: A method for the preparation of 2-[4-(4-hydroxy-3-carboxyphenylazo)-benzenesulfonamido]-pyridine by reacting 4-diazobenzenesulfonic acid with an ester of salicyclic acid having the formula ##STR1## in the presence of an alkali metal hydroxide to form a first reaction product having the formula ##STR2## reacting said first reaction product with an acylating agent to form a second reaction product having the formula ##STR3## treating said second reaction product with thionyl chloride in the presence of a tertiary formamide to form a chlorinated compound having the formula ##STR4## reacting said chlorinated compound with 2-amino-pyridine under water-free conditions in the presence of an acid binding agent, to form a third reaction product having the formula ##STR5## treating said third reaction product with alkali metal hydroxide in the presence of water to hydrolyze off the R and R.sub.1 groups, and recovering 2-[4-(4-hydroxy-3-carboxyphenylazo)-benzenesulfonamido]-pyridin e.