Fluorine Containing Bioactive Heterocycles. Part III: Synthesis of Some New Fluorine Containing Phenylglyoxals and 1,2,4-Triazine Derivatives

Joshi, Krishna C.; Dubey, K.; Dandia, Anshu

doi:10.3987/r-1981-09-1545

Cited by 9 publications

(4 citation statements)

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“…As a result, the 5,6,7,8‐tetrafluoro‐1 H ‐pyrazolo[3,4‐ b ]quinolines were synthesized, applying the reaction used earlier for the preparation of substituted acridines . The results of the Abramov et al study on the reaction of pentafluorobenzaldehyde with 1 H ‐pyrazol‐5‐amines seem to be different from those found earlier by Joshi et al , who obtained bis ‐pyrazolo[3,4‐ b ,4′,3′‐ e ]pyridines ( BPP ), rather than PQ, in a similar reaction performed in non‐solvent conditions at 220–240°C. They only proved the structures of the products by using elemental analysis of nitrogen (with no apparatus details), neither 1 H‐NMR nor 13 C‐NMR spectra were present, and the melting point of the suggested product, 1,3,5,7‐tetraphenyl‐4‐(pentafluorophenyl)‐ bis ‐pyrazolo[3,4‐ b ,4′,3′‐ e ]pyridine, is similar to that found for the 5,6,7,8‐tetrafluoro‐1 H ‐pyrazolo[3,4‐ b ]quinoline by Abramov.…”

Section: Introductionmentioning

confidence: 81%

Facile and Regioselective Synthesis of Substituted 1H‐Pyrazolo[3,4‐b]quinolines from 2‐Fluorobenzaldehydes and 1H‐Pyrazol‐5‐amines

Szlachcic

Kucharek

Jarosz

et al. 2016

Journal of Heterocyclic Chem

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The present article concerns the scope and limitations of the regioselective condensation of 2‐fluorobenzaldehydes with 1H‐pyrazol‐5‐amines, leading to the synthesis of substituted 1H‐pyrazolo[3,4‐b]quinolines (PQ), in the presence of a base catalyst (DABCO and 2,4,6‐trimethylpyridine). A method to obtain these nitrogen heterocycles with fluorine or trifluoromethyl substituents in different positions in the carbocyclic ring was developed as a part of a systematic research on the influence of fluorine‐containing substituents on the parameters of PQ. Those compounds, characterized by high‐fluorescence intensity, have been tested as emitters for the organic light‐emitting diodes since 1997. The functionalization of PQ causes changes in various parameters, for example, HOMO and LUMO levels, which are important for the adjustment of fabricated organic light‐emitting diodes. One of the easiest methods of PQ preparation, namely, the condensation of substituted anilines with 5‐chloro‐1H‐pyrazole‐4‐carbaldehydes, is not regioselective. The method described in this study allows synthesizing of 1H‐pyrazolo[3,4‐b]quinolines with good yields and high selectivity – only the expected isomer is obtained. As various different 2‐fluorobenzaldehydes are commercially available, and 1H‐pyrazol‐5‐amines with different substituents are easy to prepare, the method could be a good alternative to the already known procedures. All possible mechanisms of the reaction were also thoroughly studied.

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Section: Introductionmentioning

confidence: 81%

Facile and Regioselective Synthesis of Substituted 1H‐Pyrazolo[3,4‐b]quinolines from 2‐Fluorobenzaldehydes and 1H‐Pyrazol‐5‐amines

Szlachcic

Kucharek

Jarosz

et al. 2016

Journal of Heterocyclic Chem

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“…There are other reports on similar condensation reactions of AGs with substituted amidrazones for construction of 1,2,4-triazines in the literature …”

Section: Synthesis Of Six-membered Heterocyclesmentioning

confidence: 96%

Arylglyoxals in Synthesis of Heterocyclic Compounds

2013

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“…Pyrazolo[3,4‐ b ]pyridines as aza‐analogues of indazoles are attractive targets in organic synthesis because of their significant biological activities, such as hypoglycemic [1], psychotropic [2], cytotoxic [3], antiviral [4], fungicidal [5], antiasthmatic [6], antiallergic [7], antitumor [8], and antibacterial [9]. These compounds were also used in coronary of neurodegenerative diseases [10, 11].…”

Section: Introductionmentioning

confidence: 99%