ZrCl 4 -Catalysed Synthesis of New 4-(2-hydroxyphenyl)Pyrazolo[3,4-b]Pyridine Derivatives

In the presence of a catalytic amount of zirconium(IV) chloride, an efficient synthesis of new 4-(2-hydroxyphenyl)pyrazolo[3,4-b]pyridines has been developed by the reaction 2-hydroxychalcones with 3-methyl-1-phenyl-1H-pyrazol-5-amine in refluxing ethanol. All these novel compounds have been characterised by ¹H NMR, ¹³C NMR, HRMS, IR spectra and X-ray crystallographic analysis.