Sulfidation of Heterocyclic 1,3-Dicarbonyl Systems .

Anions of heterocyclic five-or six-membered 1,3-dicarbonyl systems react with aromatic disulfides and other -S-S- systems, such as dithiuramdisulfides in DMF in the presence of potsssium carbonate to yield sulfides. The heterocyclic systems studied include pyrazol-1,3-diones, barbituric acid [1], 6-hydroxy-3(2H)-pyridazinones [2], 4-hydroxy-2-pyrones, 4-hydroxy-2-pyridones, and their benzo derivates (e.g. coumarins and 2-quinolones [3]). Oxidation of the aromatic sulfides with peracids yields sulfones, while careful oxidation with hydrogenperoxide in alkaline medium affords the sulfoxides. The latter class of compounds are heteroanalogs of the well known cyclic tricarbonyl methane derivatives (SO instead of CO) which show a broad range of biological activity, especially in agricultural chemistry.