Synthesis of diarylsulphide-/diarylselenide-embedded pyrazole-fused isocoumarins and isatin/ninhydrin hydrazones via acid-catalyzed solvent- and temperature-controlled reactions†

Room temperature stirring of a mixture of chalcogenated arylhydrazones and ninhydrin in dichloromethane (DCM) in the presence of acid leads to the formation of pyrazole-fused isocoumarins, substituted with a diarylsulphide/diarylselenide moiety. On the other hand, refluxing the same mixture in the protic polar solvent ethanol with acid produces diarylsulphide/diarylselenide containing ninhydrin hydrazones. Further study reveals that, like ninhydrin, isatin can also generate the corresponding chalcogenated hydrazones at the C-3 position under similar reaction conditions.