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.
Key words
heterocycles - nitriles - cyclization - chemoselectivity - hydrazones