Synthesis of Some Novel Pyrazolopyridooxazine, Pyrazoloquinolizines, Pyrazoloindolizine and Pyrazolopyranopyrimidinone Derivatives

Abstract

Several heterocyclic compounds containing pyrazole ring are very useful as intermediates for pharmaceuticals 1-4 and have shown several biological activities such as antiinflammatory agents 5-7 , antibacterial 8-12 , antifungal 9 , antiviral 13,14 , antitumor 15-19 and insecticidal 20,21. Numerous pyrazole derivatives are also used in dye industry 22. In our continued interest in the development of highly expedient methods for the synthesis of diverse heterocyclic compounds of biological significance, we report herein the synthesis of some novel pyrazole derivatives which are pyrazolinoquinolizines, 1,4-oxazinopyrazolines, 6-amino-1,4dihydro-pyrano[2,3-c]pyrazole-5-carbonitrile and 4,6dihydropyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidin-5(1H)-one. Moreover, in some cases we used a one pot multicomponents reaction using microwave and ultrasound irradiation. EXPERIMENTAL Melting points were determined using an Electrothermal IA9000 series digital capillary melting point apparatus and are uncorrected. IR spectra were obtained as KBr discs on a 1000-Perkin Elmer FT-IR spectrophotometer. 1 H NMR and 13 C NMR spectra were recorded on a JEOL ECP-300 NMR in CDCl3 (or DMSO-d6) using TMS as an internal standard. Chemical shifts are given in ppm on the δ scale and coupling constants (J) are given in Hz. Electron impact (EI) MS spectra were acquired with the aid of a Shimadzu GCMSQP5050A spectrometer, equipped with a 30 m × 0.25 mm DB-1 glass column, operating with an ionization energy of 70 eV, at the