Facile Synthesis of Hydrazine Derivatives of 5H-Pyrrolo[3,4-b]pyrazine and 1H-Pyrrolo[3,4-b]quinoxaline

A convenient and efficient route for the chemoselective synthesis of carbohydrazide, arenesulfonylhydrazide, and thiosemicarbazone derivatives of 5H-pyrrolo[3,4-b]pyrazine and 1H-pyrrolo[3,4-b]quinoxaline from the corresponding dinitriles and substituted hydrazines was elaborated. The synthesis of starting pyrazine-2,3-dicarbonitrile was sufficiently improved by using concentrated HCl as a catalyst.