Studies on solid state reaction of 1-phenyl-3-methyl-5-pyrazolone with dicarbonyl compounds

The solid state reactions of benzil, p-dimethylaminobenzil, 4,4′-dibromobenzil, p-dimethylaminobenzoin and o-phthalimide with 1-phenyl-3-methyl-5-pyrazolone were reported. This thermal reaction was carried out at 120°C for 0. 5 h and gave one of the 1 : 1 condensation isomers in a higher selectivity. The structures of seven new products were identified by IR, ¹H NMR, MS and elementary analysis, and the configuration of the product 1-phenyl-3-methyl-4-benzoylphenylmethylene-5-pyrazolone 1 was determined by X-ray diffraction analysis. In the molecule of compound 1, there is four plans rather than coplanar. Benzoyl group and CO group of five membered ring are in cis-positions, the interaction of oxygen atoms leads to noncoplanar.