Synthesis and characterization of 2-(1-phenyl-5-aryl-4, 5-dihydro-3-pyrazolyl)-6-chloro-5-fluoro-3-phenylindoles and 2-(1-phenyl-5-aryl-3-pyrazolyl)-6-chloro-5-fluoro-3-phenylindoles

Phenyl hydrazone of 3-chloro-4-fluoro aniline 1 was obtained by coupling the diazonium chloride of chlorofluoro aniline with ethyl-α-benzyl acetoacetate in the presence of sodium acetate under the condition of modified Japp-Klingemann reaction. On passing hydrogen chloride gas for 1 hr the hydrazone underwent Fischer indole cyclization to give 2-acetyl-6-chloro-5-fluoro-3-phenylindole 2. It was then condensed with various aromatic aldehydes in the presence of sodium hydroxide in ethanol to get substituted chalcones 3a-g. Chalcones 3a-g were brominated to get dibromo chalcones 4a-g. Chalcones 3a-g were treated with phenyl hydrazine in presence of triethylamine to get title compounds 5a-g. Dibromo chalcones 4a-g were treated with phenyl hydrazine in triethanol amine to get title compounds 6a-g.