General Issue ARKIVOC 2011 (ii) 240-251 Synthesis of new pyrazolo[3,4-b]pyridin-3-ones and pyrazolo[1,5- a]pyrimidin-2(1H)-one and study of the pyrazolic nitrogen reactivity Salah Fadel, a Salha Hamri, a Youssef Hajbi, a,b Franck Suzenet, b Abderrafia Hafid, a El-Mostapha Rakib, a Mostafa Khouili, *a Maria D. Pujol, c and Gérald Guillaumet b a Laboratoire de Chimie Organique et Analytique, FST Beni-Mellal, BP 523, 23000 Beni-Mellal, Université Sultan Moulay Slimane, Morocco b Institut de Chimie Organique et Analytique (ICOA), UMR-CNRS 6005, BP 6759, 45067 Orléans Cedex 2, Université d’Orléans, France c Laboratori Química Farmacèutica, Facultat de Farmàcia (Unitat Associada al CSIC), 08028, Barcelona, Universitat de Barcelona, Spain E-mail: mkhouili@yahoo.fr Abstract A convenient route to the synthesis of pyrazolo[3,4-b]pyridin-3-one and pyrazolo[1,5- a]pyrimidin-2(1H)-one via condensation of 3-amino-1-phenylpyrazolin-5-one with 2-pyrone derivatives followed by the alkylation of prepared compounds is described. Several reactions conditions were carefully studied. Keywords: Pyrazolone, 2-pyrone, pyrazolo[3,4-b]pyridin-3-one, pyrazolo[1,5-a]pyrimidin- 2(1H)-one Introduction The interest for the synthesis of the pyrazolo[3,4-b]pyridine and pyrazolo[1,5-a]pyrimidine has increased in organic and pharmaceutical chemistry. These heterocyclic systems are found in a number of molecules possessing biological and/or pharmacological properties. 1-6 The literature indicates different synthetic approaches to these compounds and mentions two main processes: one reported by Kuczynski for the preparation of 3-aminopyrazolo[3,4-b] pyridines by reaction of 2-chloro-nicotinonitrile with some hydrazines in xylene or ethanol at reflux. 7 The same reaction was performed in the laboratory under milder conditions in the presence of copper iodide complexed with o-phenanthroline as catalyst, leads to excellent yields. 8 And others have been described by Quiroga on the condensation of the aminopyrazole with α,β-unsaturated Page 240 © ARKAT-USA, Inc.