A simple means of preparing quinoxaline derivatives: direct introduction of C-nucleophiles into the quinoxaline nucleus by substituting a hydrogen atom

Unsubstituted quinoxaline (I) reacts with dimedone, indanedione, and 1-phenyl-3-methylpyrazol-5-one in dimethylsulfoxide in the presence of acid to form monosubstitution products II – IV. Quinoxaline reacts with 1,3-dimethylbarbituric acid in dimethylsulfoxide solution at room temperature to form monosubstitution product V without external catalysis. Heating of I with resorcinol in ethanol in the presence of acid produced resorcinol derivative VI. In the presence of base, quinoxaline reacts with 1-phenyl-3-methylpyrazol-5-one to form dipyrazolylmethane VII and tetrapyrazolylethane derivative VIII. Compound VIII undergoes cleavage to form dipyrazolylmethane VII in dimethylformamide solution with boiling or in the presence of iodine at room temperature.