Synthesis of novel hydropyrazolopyridine derivatives in solvent-free conditions via benzotriazole methodology (original) (raw)
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Synthetic Communications, 2018
The versatile, 3-aminopyrazolo[4,3-c]pyridine-4,6-dione (2) was synthesized and allowed to react with aldehydes, aryldiazonium chlorides, chalcones and enaminones to afford regioselectively the novel pyrazolo [4,3-c]pyridine derivatives 4a-c, pyrazolo[4,5,1-ij][1,6] naphthyridines 9a-d and pyrido[4',3':3,4]pyrazlo[1,5-a]pyrimidines 19a-i. The structure of all the newly synthesized compounds was assigned from elemental analysis and spectral data. Also, the mechanistic aspects for the formation of the newly synthesized compounds is discussed.
ynthesis of some new 2,6-bis pyridines functionalized with tetra-substituted pyrazole heterocycles
Several new tetra-substituted pyrazoles attached to pyridine nucleus at positions 2 and 6 were synthesized from the reactions of2,6-bis(ethoxycarbonyl-acetyl)pyridine (2) with different series of hydrazonoyl chlorides including; C-acetyl-N-aryl-hydrazonoyl chlorides (3a-c) and (Cethoxycarbonyl)-N-aryl-hydrazonoyl chlorides (12a-c). The structures of the synthesized products were established on the basis of their elemental analysis and spectral data in addition to, the chemical behavior of the reaction products with hydrazine hydrate to afford the corresponding pyrazolo[4,3-d]pyridazine derivative.
An Efficient Synthesis of Novel Pyrazole-Based Heterocycles as Potential Antitumor Agents
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A new series of pyrazolylpyridines was prepared by reaction of ethyl-3-acetyl-1,5-diphenyl-1H-pyrazole-4-carboxylate with the appropriate aldehyde, malononitrile, or ethyl acetoacetate and an excess of ammonium acetate under reflux in acetic acid. Similarly, two novel bipyridine derivatives were prepared by the above reaction using terephthaldehyde in lieu of benzaldehyde derivatives. In addition, a series of 1,2,4-triazolo[4,3-a]pyrimidines was synthesized by a reaction of 6-(pyrazol-3-yl)pyrimidine-2-thione with a number of hydrazonoyl chlorides in dioxane and in the presence of triethylamine. The structure of the produced compounds was established by elemental analyses and spectral methods, and the mechanisms of their formation was discussed. Furthermore, the pyrazolyl-pyridine derivatives were tested as anticancer agents and the results obtained showed that some of them revealed high activity against human hepatocellular carcinoma (HEPG2) cell lines.
Acta pharmaceutica (Zagreb, Croatia), 2004
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.
A new convenient synthesis of some novel 2,6-disubstituted-pyridine derivatives
Arkivoc, 2010
The versatile, hitherto unreported pyridine-2,6-bis-(3-oxo-3-propanenitrile) 2 was prepared by the Claisen condensation of pyridine-2,6-dicarboxylic acid ester 1 with acetonitrile in the presence of sodium hydride. Several new pyrazoles, isoxazoles, and pyrazolopyridazine derivatives have been synthesized by the reaction of pyridine-2,6-bis-(3-oxo-3-propanenitrile) 2 with bidentate nucleophilic reagents and hydrazonoyl chloride derivatives.
Molecules, 2014
4-Imino-1-p-tolyl-1,4-dihydropyrazolo[3,4-d]pyrimidin-5-ylamine (2) and (1-ptolyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl)-hydrazine (3) were prepared starting from ethyl 4-cyano-1-p-tolyl-1H-pyrazol-5-ylimidoformate (1). The structure of compound 3 was confirmed through preparation of the pyrazole derivatives 4 and 5. Also, the synthesis and structural characterization of pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidine derivatives 7 and 9 and their isomerization to pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives 6 and 8, respectively, under different suitable reaction conditions were reported. Moreover, the syntheses of 2-substituted-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives 10 and 11 was described.
Synthesis of new pyrazole and antibacterial pyrazolopyrimidine derivatives
TURKISH JOURNAL OF CHEMISTRY, 2014
3-Substituted-1-phenyl-1 H-pyrazolo[3,4-d ]pyrimidin-4-amines 2a-c were synthesized by treating 5-aminopyrazole-4-carbonitriles 1a-c with formamide. The reactivity of compounds 1a-c towards some cyclic anhydrides was studied. The condensation of 5-aminopyrazole-4-carbonitrile 1b with triethylorthoformate gives imidate 7b, which reacts with a series of primary amines and leads to pyrazolo[3,4-d ]pyrimidine-4-amines 9 and 10. The reaction of imidate 7b with ammonia and hydroxylamine afforded pyrazolopyrimidine 2b and pyrazolo[3,4-d ]pyrimidin-5-(4 H)-ol 11, respectively. The synthesized compounds were completely characterized by 1 H NMR, 13 C NMR, IR, and HRMS. The antibacterial activity of some new synthesized compounds was evaluated and appeared to be significant.
Journal of The Iranian Chemical Society, 2018
Depending on the reaction conditions, two alternative cyclizations are possible for [3 + 3] cyclocondensation of pyrazolone derivative 1a and ethyl cyanoacetate of type pyrano [2,3-c] pyrazol-6(1H)-one 2 and pyrano [2,3-c] pyrazol-4(1H)-one 3. Keeping of enaminic system 3 and benzylidene malononitrile in the presence of catalytic amount of trimethylamine resulted in pyridine cyclization affording pyrazolopyranopyridine derivative 4, not 5. The pyrazolone derivative 6a was obtained as a result of the acid-mediated addition reaction between compound 1a, urea and/or ammonium thiocyanate. In addition, the bispyrazolone of type 6b was obtained from the condensation reaction of urea and pyrazolone derivative. The spiro compound 7 was obtained from the double-addition reaction of pyrazolone to cinnamoyl isothiocyanate. A one-pot three-component condensation of a 3-hydroxybenzaldehyde, pyrazolone 1a, urea and/or thiourea under Biginelli conditions resulted in tetrahydropyrazolo pyrimidine derivatives 8a and 8b, respectively. The acid-mediated reaction of benzaldehyde and pyrazolone derivative 1a in the presence of Ac 2 O yielded styrylpyrazole derivative 9. The polyfunctionalized product 9 reacted with hydrazine to furnish pyrazolotriazoloe of type 10. Treatment of styrylpyrazole derivative 9 with aniline furnished the aniline derivative 11 and none of the expected polyheterocyclic derivative 12 was obtained. Compound 9 undergoes pyridine cyclization to produce 13 under the effect of urea. N-phenyl pyrazolone converted into pyrano-dipyrazolone derivative 14. Pyran of type 14 underwent a ring transformation upon treatment with urea and/or thiourea to give the same dipyrazolo pyrimidine derivative 15. The newly synthesized compounds were characterized by FT-IR, 1 H-NMR, 13 C-NMR, ESI/LC-MS and elemental analysis.