Acta Pharm. 54 (2004) 143-150[ Full paper in PDF ]
The bifunctional pyrazolopyridine (2) and pyrano-pyrazole (3) derivatives were prepared by the reaction of 2-(2,4-dinitrophenyl)-5-methyl-2,4-dihydro-3H-pyrazol-3-one (1) with p-methoxybenzaldehyde, malononitrile in the presence of ammonium acetate or piperidine, respectively. Compound 2 was used as the key intermediate to prepare the pyrazolo-pyrido-pyrimidine derivatives through its reaction with formic acid, formamide-formic acid-DMF, ammonium thiocyanate or reaction with triethyl orthoformate followed by cyclization with hydrazine hydrate. Reaction of 3 with triethyl orthoformate followed by cyclization with hydrazine hydrate gave the pyrazolo-pyrano-pyrimidine derivative 11. Reaction of ethyl-3-oxo-2-[2-phenyl-diazenyl]butanoate and ethyl 2-[2-(4-chlorophenyl)diazenyl]-3-oxobutanoate with 1 to give the pyrazolone derivatives 13a and 13b was also considered.
Keywords: pyrazolopyridine derivatives, pyranopyrazole derivatives, synthesis