| Abstract: | The reaction of o-phenylenediamine with a β-ketoacid, leads in most cases to quinoxalinones. Their structure has been determined as well as that of their corresponding hydrazones. The reaction of hydrazine with these quinoxalinones gives dihydropyridazino3,4-b]quinoxalines, the structure of which has been ascertained. It has been shown that among the six possible formulas, the only 1,2-dihydro structure fits with the spectroscopic data. On the contrary, N-substituted o-phenylenediamines lead to 2,10-dihydro derivatives. The electrochemical behavior of the 2,10-dihydro-10-methyl-3-phenylpyridazino3,4-b]quinoxaline has been investigated. It has also been shown that the 3,4,6-trichloropyridazine reacts with o-phenylenediamines to give 5,10-dihydropyridazino3,4-b]quinoxalines. These compounds can be oxidized to give the new heterocycle pyridazino3,4-b]quinoxaline. |
