ABSTRACT A convenient route has been developed for the synthesis of new nitrogenous heterocyclic compounds containing the subastpyrazolo[3,4-b]pyridine nucleus, by condensation reaction of 5-amino-3-methyl-1-phenyl-1H-pyrazole (1) with 4-hydroxy-6-methylpyran-2-one (2). Various reaction conditions were carefully studied. The reaction depends on the solvent used and when it is acetic acid a mixture of 3 and 5 is formed. Pyrazolopyridine 3 was obtained with better yields when the condensation of 2 and 1 was carried out using methanol as a solvent and with the presence of p-toluene sulfonic acid (PTSA) and assisted by microwave irradiation.
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