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Title: | An Unequivocal Synthesis of 2-Aryl Substituted 3-Amino-2,4,5,7-tetrahydro-6H-pyrazolo[3,4-b]pyridin-6-ones |
Author: | Bou-Petit, Elisabeth Picas, Elsa Puigjaner Vallet, Ma. Cristina Font Bardia, Ma. Mercedes Ferrer, Nabí Sempere, Julià Puig de la Bellacasa, Raimon Batllori, Xavier Teixidó, Jordi Estrada-Tejedor, Roger Ramon y Cajal, Santiago Borrel, José I. |
Keywords: | Química orgànica Compostos cíclics Organic chemistry Cyclic compounds |
Issue Date: | May-2017 |
Publisher: | Wiley-VCH |
Abstract: | The 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. |
Note: | Versió postprint del document publicat a: https://doi.org/10.1002/slct.201700732 |
It is part of: | Chemistryselect, 2017, vol. 2, num. 13, p. 3668-3672 |
URI: | http://hdl.handle.net/2445/163391 |
Related resource: | https://doi.org/10.1002/slct.201700732 |
ISSN: | 2365-6549 |
Appears in Collections: | Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada) |
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