A new synthetic entry to fused azaquinones by a cycloaddition/ring transformation sequence starting from pyrido[1,2-a]pyrazines

Billert, Thomas; Beckert, Rainer; Fehling, Peer; Döring, Manfred; Görls, Helmar

doi:10.1016/s0040-4020(97)00239-1

Cited by 18 publications

(8 citation statements)

References 9 publications

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“…A solution of 0.24 g (2.2 mmol) of phenylhydrazine in methanol (5 ml) was added to a stirred solution of 0.43g (2 mmol) of compound 11a in methanol (25 ml ,4.26;N,13.67. Found: C,66.21;H,4.19;N,13.96. 4-Methoxy-5-phenyl-3-(phenylhydrazono)-3H-pyridine-2,6dione (21).…”

Section: X-ray Diffraction Analysis Of 15amentioning

confidence: 99%

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New azabenzoquinones by ring‐expansion reactions

Poschenrieder¹,

Stachel²,

Wiesend³

et al. 2003

Journal of Heterocyclic Chem

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Ozonolysis of the pyrrolidinediones 4 afforded the pyrrolidinetriones 5, which in the presence of Lewis acids were converted into maleimide 6. Analogously, ozonolysis of the pyrrolidinones 7 gave the pyrrolidinediones 8, which were converted into the pyridinetriones 11a, b via Lewis acid catalyzed isomerization to yield the trihydroxypyridones 10 and ensuing air oxidation. In solution two tautomeric forms of the pyridinetriones 11 may exist both of which represent hydroxy-azabenzoquinones. In two steps compounds 11 were transformed into the azaquinone derivatives 19. Representatives of another type of azaquinones are compounds 28a, b. These were generated in two steps from the pyridones 25. The azaquinone 28a reacted easily with acidic compounds yielding the adducts 26, 27 and 29 or with 2-butenal forming the cycloadduct 30.

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Section: X-ray Diffraction Analysis Of 15amentioning

confidence: 99%

“…Deviating from the above definition the term azaquinone was sometimes used for quinone imines in the literature [12]. Nomenclatory difficulties also exist with the designation of quinones with fused heterocycles as azaquinones [13].…”

Section: Introductionmentioning

confidence: 99%

New azabenzoquinones by ring‐expansion reactions

Poschenrieder¹,

Stachel²,

Wiesend³

et al. 2003

Journal of Heterocyclic Chem

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“…Exemplarisch sei hier deren Umwandlung mit Acetylendicarbonsäureestern zum 2,2'-Bipyridin 10 vorgestellt. Die bereits an Verbindungen 1 studierte Cyloadditions-Ringtransformations-Sequenz [2] bietet auch hierbei Grundlage mechanistischer Interpretationen. Die in guter Ausbeute isolierbaren Pyrido-pyrrolinone 10 sind wiederum Ausgangspunkt für eine vielseitige Folgechemie.…”

Section: ____________________________________________________________unclassified

“…Triazinderivaten [2,3]. Ihre ausgeprägte Neigung zu Cycloadditions-und Ringtransformationsreaktionen mit elektronenarmen Mehrfachbindungssystemen macht diese Substanzklasse für die Synthese hochsubstituierter Heterocyclen attraktiv.…”

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Beiträge zur Chemie der pyrido[1,2-a]pyrazine - Reaktivität gegenüber Heterocumulenen der Kohlensäurereihe und Ketenen

et al. 1999

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Vor kurzem berichteten wir über den einfachen Zugang zu substituierten Pyrido[1,2-a]pyrazinen vom Typ 1 durch eine Ringschlußreaktion von Bis(imidoyl)chloriden der Oxalsäure mit 2-Aminomethylpyridin [1] sowie deren Transformation zu hochfunktionalisierten Azachinonen und Oxadiazin-bzw. Triazinderivaten [2,3]. Ihre ausgeprägte Neigung zu Cycloadditions-und Ringtransformationsreaktionen mit elektronenarmen Mehrfachbindungssystemen macht diese Substanzklasse für die Synthese hochsubstituierter Heterocyclen attraktiv. Da letztere aufgrund ihrer Möglichkeiten zur Ausbildung von Wasserstoffbrücken und/oder von Metallkomplexen in der Supramolekularen Chemie eine zentrale Stellung einnehmen, besteht Interesse an neuen und effektiven Synthesen für derartige Systeme. Im folgenden Teil werden neuartige Derivatisierungen und Ringtransformationen der Pyrido[1,2-a]pyrazine vorgestellt. Heterometathesen mit Isocyanaten, Isothiocyanaten und IsoselenocyanatenNeben Chinonen [2], Nitrosoverbindungen und Derivaten der Diazodicarbonsäure [3] sollten Reaktionen acceptorsubstituierter Heterocumulene der Kohlensäu-Abstract. In order to extend the ring transformation reactions of pyrido[1,2-a]pyrazines 1 which contain a cyclic 2aza-1,3-diene substructure acceptor-substituted heterocumulenes 2 have been tested as dienophiles. In contrast to other reactions described to date, exclusively the exocyclic imino function was attacked. In the course of a hetero-metathesis the new aryl-(4-thiono-4H-pyrido[1,2-a]pyrazin-3-yl)amines 4Ra and aryl-(4-selono-4H-pyrido[1,2-a]pyrazin-3-yl)amines 4Rb were formed. In the case of isocyanates of type 2e and 2f the preliminary [2+2]-cycloaddition reaction prefera-332

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“…For example, starting from cycloamidines of type 1 by a cycloaddition/ring transformation sequence new compounds such as 2,2-bipyridines [2], azaquinones [3], 1,2,4-triazines [4] and 1,2,5-oxadiazines [4] are accessible. Our work in this area is aimed at the synthesis of further pyridine derivatives, and the 2-hydrazinopyridine 3, 1,2-diaminopyridinium iodide 4 and 1-amino-2-methylpyridinium iodide 5 were chosen as starting materials.…”

Section: Introductionmentioning

confidence: 99%

New heterocycles with cycloamidine substructure and their ringtransformation reactions with acetylene dicarboxylic ester

Billot

Beckert

Döring

et al. 2001

Journal of Heterocyclic Chem

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The synthesis of pyrido[2,1-c]-1,2,4-triazines 6, pyrido[1,2-b]-1,2,4-triazines 7 and pyrido[1,2-b]pyridazines 8 respectively by cycloacylation of derivatives of pyridine with imidoylchlorides of type 2 is described. The heterocycles of type 6 as well as of type 7 can be ring-transformed with dimethyl acetylenedicarboxylate. In contrast to pyrido[1,2-a]pyrazines 1, a complex reaction including cleavage of the acetylene subunit takes place. Starting from compound 6a, the pyrrolo[2,3-d]imidazole 11a could be isolated from a mixture of unidentified by-products, whereas derivatives 7 gave nearly quantitatively the tricyclic products of type 12.

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A new synthetic entry to fused azaquinones by a cycloaddition/ring transformation sequence starting from pyrido[1,2-a]pyrazines

Cited by 18 publications

References 9 publications

New azabenzoquinones by ring‐expansion reactions

New azabenzoquinones by ring‐expansion reactions

Beiträge zur Chemie der pyrido[1,2-a]pyrazine - Reaktivität gegenüber Heterocumulenen der Kohlensäurereihe und Ketenen

New heterocycles with cycloamidine substructure and their ringtransformation reactions with acetylene dicarboxylic ester

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