2000 pyrazole derivatives

pyrazole derivativesR 0180

05 - 131Anionic [4 + 2] Cycloaddition Reactions of Dihydropyrazolin-5-oneDienolate with Dienophiles: A Novel Approach for Substituted andFused Indazolones. — Dihydropyrazolin-5-one dienolate, in situ generatedfrom 4-formylantipyrine (I), is an efficient anionic pyrazolone o-quinodimethaneequivalent, which undergoes facile regioselective cycloaddition with electron-deficient dienophiles, e.g. (II), (IV), (VI), (VIII), and (X), to afford substitutedor fused indazolones in good yields. — (ROY, AMRITA; REDDY, KETHIRIR.; ILA, HIRIYAKKANAVAR; JUNJAPPA, HIRIYAKKANAVAR; J. Chem.Soc., Perkin Trans. 1 (1999) 20, 3001-3004; Dep. Chem., Indian Inst. Technol.,Kanpur 208 016, India; EN)

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