Synthesis and characterization of some amino pyrazole compounds containing phosphonate group

Pyrazole derivatives are heterocyclic compounds having synthetic origin and found rarely in the nature. Various biological activities has made it significant of synthesis of these compounds. One of the important pyrazole derivatives are amino pyrazole compounds. On the other hand phosphonate and phosphonic acid derivatives, an important class of compounds representing the organophosphour has a wide range of applications in both medical and agricultural areas because of their potential biological activities. In this study, 4-bromophenyl acetonitrile was used as the starting compound for palladium catalysed cross coupling reactions carried out in the subsequent steps. 1,3-ketonitrile derivatives (BS-1) were obtained via reacting the starting compounds with various ethylesters. These compounds were reacted with some hydrazine derivatives to obtain 5-amino pyrazoles (BS-2). After these steps, two different synthetic routes were followed. Firstly, some of the amino pyrazoles were converted to compounds carrying an aldehyde functional group (BS-3) by Suzuki-Miyaura reaction and then to α–hydroxyphosphonate compounds (BS-5) by Pudovik reaction and α–aminophosphonate compounds (BS-6) by Kabachnik-Fields reaction. Bromine containing amino pyrazoles are also converted to arylphosphonate derivatives (BS-4) by Hirao reaction. At the end, phosphonic acid derivatives (BS-7, BS-8, BS-9) were obtained by hydrolizing all of the phosphonate compounds already synthesized. In conclusion, some heterocyclic compounds having biological activity potential by virtue of containing both amino pyrazole and phosphonic acid were synthesized for the first time. Structures of all the synthesized compounds were verified by 1H NMR, 13C NMR, 19F NMR, 31P NMR spectrums and structures of some selected compounds by IR and X-ray diffraction spectrums additionally.