ASIAN JOURNAL OF CHEMISTRY, cilt.15, sa.3, ss.1373-1379, 2003 (SCI-Expanded)
Furan-2,3-diones (1a-c) react with various hydrazines (2a-d) in boiling benzene to yield the pyrazole-3-carboxylic acids (3a-c) and the 1,2-dihydropyridazine-3,4-diones (6a-d). The structures of all products were confirmed by elemental analysis, IR, H-1- and C-13-NMR spectroscopic measurements. Thermal decomposition of 4-benzoyl-1-(2,4-dinitrophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid (3b) leads to the formation of [1-(2,4-dinitrophenyl)-5-phenyl-1H-pyrazol-4-y1]phenylmethanone (5). The pyrazole-3-carboxylic acid chloride (4) was obtained from the reaction of 3a and thionyl chloride.