The condensation of isatin with o-phenylenediamine has been studied in various kinds of solvents. The reaction gave pure indolo[2,3-b]quinoxaline (1) in acidic solvents, while it gave a mixture containing at least two out three compounds, 1, an anil and a spiro compound, in neutral or basic organic solvents. The anil and spiro compounds were converted to 1 in the presence of acid or by heating them
Refluxing dimethyl acetylenedicarboxylate (DMAD) or 1,2-dibenzoylacetylene with isatin-3-thiosemicarbazone or isatin-3-thiocarbohydrazone in methanol produced 3-substituted oxindoles in good yields. Reaction of equimolecular amounts of 5,6-diamino- urasil-solfate, trans-(1R,2R)-diaminocyclohexane, and 3,4-diamino-1,2,4-triazol-5-methyl hydrochlorid with isatin in ethanol (85%) afforded tetracyclic ring systems and ring-opened products in mild reaction conditions.
An easy and efficient protocol for the condensation reaction of isatin and <i>N</i>-substituted isatins with 1,2-diaminobenzene using low cost reusable clay catalyst
Abstract A green procedure was developed for the condensation of isatin and N-substituted isatins with 1,2-diaminobenzene by using reusable bentonite clay in EtOH/H2O solvent system, under microwave irradiation. This eco-friendly synthesis is characterized by high yields and short reaction times. The catalyst is easily recycled.