Chemical and electrochemical reduction of pyrazino[2,3-b]quinoxalines

Abstract

The hydrogenation of 2,3-dimethylpyrazino[2,3-b]quinoxaline 1 and 2-phenylpyrazino[2,3-b]quinoxaline 2 leads to the corresponding 5,10-dihydroderivatives 3b and 4b. LiAlH4 reduction of 2, of 2,3-dimethyl-6,7-diphenylpyrazino[2,3-b]pyrazine 8 and 2,6,7-triphenylpyrazino[2,3-b]pyrazine 9 furnishes the corresponding 1,2,3,4-tetrahydroderivatives 7, 10, and 11. NaBH4 reduction of 2 leads to a mixture of 4b and 7. In hydroorganic medium 1 and 2 are electrochemically reduced to 3b and 4b with which they form a redox system.