REACTION OF PYRAZOLE ADDITION TO QUINONES

The reactions of pyrazole, 4-nitropyrazole, 3,5-dimethylpyrazole, and 4-chloro-3,5-dimethylpyrazole with 1,4-benzoquinone in dioxane have been analyzed. Mono- and 2,3-bis-adducts were obtained and only in the case of pyrazole was a 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene formed. Further oxidation of the mono- and bis-adducts with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) afforded the quinones, which in turn added 1 mol of azole (pyrazole and imidazole) to yield tetrapyrazolylquinols. Nitration of the 2,3-bis(pyrazol-1-yl)- and 2,3-bis(3,5-dimethylpyrazol-1-yl)-1,4-dihydroxybenzenes has been performed to prepare the corresponding 4-nitropyrazolyl derivatives.