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Tuning of Chemo- and Regioselectivities in Multicomponent Condensations of 5-Aminopyrazoles, Dimedone, and Aldehydes

Tuning of Chemo- and Regioselectivities in Multicomponent Condensations of 5-Aminopyrazoles, Dimedone, and Aldehydes

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CHEBANOV, Valentin A., Vyacheslav E. SARAEV, Sergey M. DESENKO, Vitaliy N. CHERNENKO, Irina V. KNYAZEVA, Ulrich GROTH, Toma N. GLASNOV, C. Oliver KAPPE, 2008. Tuning of Chemo- and Regioselectivities in Multicomponent Condensations of 5-Aminopyrazoles, Dimedone, and Aldehydes. In: The Journal of Organic Chemistry. 73(13), pp. 5110-5118. ISSN 0022-3263. eISSN 1520-6904

@article{Chebanov2008Tunin-1048, title={Tuning of Chemo- and Regioselectivities in Multicomponent Condensations of 5-Aminopyrazoles, Dimedone, and Aldehydes}, year={2008}, doi={10.1021/jo800825c}, number={13}, volume={73}, issn={0022-3263}, journal={The Journal of Organic Chemistry}, pages={5110--5118}, author={Chebanov, Valentin A. and Saraev, Vyacheslav E. and Desenko, Sergey M. and Chernenko, Vitaliy N. and Knyazeva, Irina V. and Groth, Ulrich and Glasnov, Toma N. and Kappe, C. Oliver} }

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:bibo="http://purl.org/ontology/bibo/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsd="http://www.w3.org/2001/XMLSchema#" > <rdf:Description rdf:about="https://kops.uni-konstanz.de/rdf/resource/123456789/1048"> <dc:creator>Saraev, Vyacheslav E.</dc:creator> <dcterms:issued>2008</dcterms:issued> <dcterms:title>Tuning of Chemo- and Regioselectivities in Multicomponent Condensations of 5-Aminopyrazoles, Dimedone, and Aldehydes</dcterms:title> <dc:contributor>Glasnov, Toma N.</dc:contributor> <dc:creator>Desenko, Sergey M.</dc:creator> <dc:contributor>Groth, Ulrich</dc:contributor> <bibo:uri rdf:resource="http://kops.uni-konstanz.de/handle/123456789/1048"/> <dc:contributor>Saraev, Vyacheslav E.</dc:contributor> <dc:creator>Kappe, C. Oliver</dc:creator> <dc:contributor>Kappe, C. Oliver</dc:contributor> <dc:contributor>Knyazeva, Irina V.</dc:contributor> <dc:contributor>Chebanov, Valentin A.</dc:contributor> <dc:creator>Chebanov, Valentin A.</dc:creator> <dc:creator>Groth, Ulrich</dc:creator> <dc:creator>Chernenko, Vitaliy N.</dc:creator> <dcterms:available rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-22T17:54:58Z</dcterms:available> <dc:creator>Knyazeva, Irina V.</dc:creator> <dcterms:bibliographicCitation>Publ. in: The Journal of Organic Chemistry 73 (2008), 13, pp. 5110-5118</dcterms:bibliographicCitation> <dc:rights>deposit-license</dc:rights> <dc:language>eng</dc:language> <dc:date rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2011-03-22T17:54:58Z</dc:date> <dc:creator>Glasnov, Toma N.</dc:creator> <dcterms:rights rdf:resource="http://nbn-resolving.org/urn:nbn:de:bsz:352-20140905103416863-3868037-7"/> <dcterms:abstract xml:lang="eng">Regio- and chemoselective multicomponent protocols for the synthesis of 1,4,6,7,8,9-hexahydro-1H-pyrazolo[3,4-b]quinolin-5-ones, 5,6,7,9-tetrahydropyrazolo[5,1-b]quinazolin-8-ones, and 5a-hydroxy-4,5,5a,6,7,8-hexahydropyrazolo[4,3-c]quinolizin-9-ones starting from 5-amino-3-phenylpyrazole, cyclic 1,3-dicarbonyl compounds and aromatic aldehydes are described. Whereas the three-component coupling in ethanol under reflux conditions provides mixtures of pyrazoloquinolinones and pyrazoloquinazolinones, the condensation can be successfully tuned toward the formation pyrazoloquinolinones (Hantzsch-type dihydropyridines) by performing the reaction at 150 °C in the presence of triethylamine base applying sealed vessel microwave or conventional heating. On the other hand, using sonication at room temperature under neutral conditions favors the formation of the isomeric pyrazoloquinazolinones (Biginelli-type dihydropyrimidines). These products are also obtained when the three-component condensation is executed in the presence of trimethylsilylchloride as reaction mediator at high temperatures. A third reaction pathway leading to pyrazoloquinolizinones in a ring-opening/recyclization sequence can be accessed by switching from triethylamine to a more nucleophilic base such as sodium ethoxide or potassium tert-butoxide. The reaction mechanism and intermediates leading to these three distinct tricyclic condensation products are discussed.</dcterms:abstract> <dc:contributor>Chernenko, Vitaliy N.</dc:contributor> <dc:contributor>Desenko, Sergey M.</dc:contributor> </rdf:Description> </rdf:RDF>

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