87277-65-4Relevant academic research and scientific papers
Studies on 2,5-Diaryl-2,4-dihydro-3H-pyrazol-3-ones. I. Synthesis of Highly Substituted 1H-Indazoles Using Tautomeric 2,5-Diaryl-2,4-dihydro-3H-pyrazol-3-ones
Matsugo, Seiichi,Saito, Mitsuo,Kato, Yohko,Takamizawa, Akira
, p. 2146 - 2153 (2007/10/02)
The reaction of 2-aryl-5-phenyl-2,4-dihydro-3H-pyrazol-3-ones (1) with acetone gave 2-aryl-4-(1-methylethylidene)-5-phenyl-2,4-dihydro-3H-pyrazol-3-ones (2) in nearly quantitative yields, and these products reacted further with acetone in the presence of triethylamine (NEt3) as a catalyst to give 1-aryl-4,6,6-trimethyl-3-phenyl-1,6-dihydropyranopyrazoles (3).Reaction of 3 with dimethyl acetylenedicarboxylate (DMAD) or diethyl acetylenedicarboxylate (DEAD) in dimethylformamide (DMF) at reflux gave 1-aryl-4-methyl-3-phenyl-1H-indazole-6,7-dicarboxylate (7) in high yields.Thus, a new and convenient route for the synthesis of highly substituted 1H-indazoles has been developed.Keywords - tautomerism; 2,4-dihydro-3H-pyrazol-3-one; 1,6-dihydropyrano-pyrazole; 1H-indazole; dimethyl acetylenedicarboxylate; diethyl acetylenedicarboxylate; condensation; Diels-Alder reaction
