| Abstract: | Oxidative Coupling of 5-Aminopyrazoles with p-Phenylenediamines By oxidative coupling of 5-amino-3-methyl-1-phenyl-pyrazole 4 with N,N-diethyl-p-phenylenediamine the 4-(4-N,N-diethylamino-phenylimino)-3-methyl-1-phenyl-2-pyrazolin-5-imin 5 is formed. 5 is oxidized very easily to the 1H-pyrazolo3,4-b]quinoxaline 6a . The Z/E-isomerism of the azomethine dye is investigated by dynamic n.m.r.-spectroscopy. 1H-Pyrazolo3,4-b]quinoxalines (6a–d) are also formed by reaction of 1,3-disubstituted 5-aminopyrazoles with p-nitroso-dialkylanilines. |
