Bou-Petit, ElisabethPicas, ElsaPuigjaner Vallet, Ma. CristinaFont Bardia, Ma. MercedesFerrer, NabíSempere, JuliàPuig de la Bellacasa, RaimonBatllori, XavierTeixidó, JordiEstrada-Tejedor, RogerRamon y Cajal, SantiagoBorrel, José I.2020-05-312020-05-312017-052365-6549https://hdl.handle.net/2445/163391The reaction between pyridones (1) and substituted hydrazines 4 can afford two different regioisomeric pyrazolo[3,4-b]pyridin - 6-ones 2 and 3 depending on the initial substitution of the methoxy group and the direction of the cyclization. In the case of phenylhydrazine 4 (R3 = Ph), we have clearly shown that the treatment of pyridones 1a-d with 4 (R3 = Ph) in MeOH at temperatures below 1408C yields, independently of the nature and position of the substituents present in the pyridone ring, the open intermediates 7a-d. When the reaction is carried at 1408C under microwave irradiation, the corresponding 2-aryl substituted pyrazolo[3,4-b]pyridines 3a-d are always formed. We have experimentally determined, using DSC techniques, the activation energies of the two steps involved in the formation of 3: a) substitution of the methoxy group present in pyridones 1 with phenylhydrazine 4 (R3 = Ph) to afford intermediates 7 and b) cyclization of intermediates 7 to yield pyrazolopyridines 3. The results obtained, 15 and 42 kcal·mol 1 respectively, are in agreement with the experimental findings.19 p.application/pdfeng(c) Wiley-VCH, 2017Química orgànicaCompostos cíclicsOrganic chemistryCyclic compoundsinfo:eu-repo/semantics/article6768522020-05-31info:eu-repo/semantics/openAccess