Reactions of 5-amino-1,2-azoles with aromatic and heterocyclic o-chloroaldehydes: [1+1] versus [2+1] cyclocondensation

Abramov, M. A.; Ceulemans, Erik; Jackers, Carine; Auweraer, Mark Van der; Dehaen, Wim

doi:10.1016/s0040-4020(01)00917-6

Cited by 27 publications

(17 citation statements)

References 33 publications

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“…5,6,7,8-Tetrafluoro-1,3-substituted-pyrazole-, isoxazole-and isothiazole-quinoline derivatives [619] are being prepared in the reaction, where the condensation of the aldehydic function and the substitution of the adjacent fluorine occur simultaneously. This leads to the cyclization products which are shown in Scheme 77.…”

Section: Cyclization Reactions Of Pentafluorobenzaldehyde Utilizing Tmentioning

confidence: 99%

Pentafluorobenzaldehyde and its utilizing in organic synthesis

Pažitný

Solčan

Végh

2009

Journal of Fluorine Chemistry

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Section: Cyclization Reactions Of Pentafluorobenzaldehyde Utilizing Tmentioning

confidence: 99%

Pentafluorobenzaldehyde and its utilizing in organic synthesis

Pažitný

Solčan

Végh

2009

Journal of Fluorine Chemistry

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“…For comparison, we also performed the reaction with pentafluorobenzaldehyde, 1k (used by Abramov et al ). As can be seen from Table , 2‐fluoro‐6‐halogen‐benzaldehydes ( 1e,f,h ) predominantly form the corresponding 5‐halogen‐1,3‐diphenyl‐1 H ‐pyrazolo[3,4‐ b ]quinoline, PQ ( 3e,f,h ), and in all cases, the fluorine atom is substituted.…”

Section: Resultsmentioning

confidence: 99%

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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“…Furthermore, Abramov et al [45] reported that treatment of 4 with 3-amino-5-methyl-2-phenyl-pyrazole, 5-amino-3-methyl-thiazole hydrochloride, or 5-amino3-methyloxazole 60a-c in a mixture of toluene/acetic acid mixture afforded the corresponding pyridines 61a-c (Scheme 13). Nucleophilic substitution reaction of 4 with morpholine 84a or N-methyl piprazine 84b in DMF/K 2 CO 3 afforded the corresponding enamine 85a, b [38].…”

Section: Reactions With Aminesmentioning

confidence: 99%