- Copper-catalyzed hydrolysis of bromoisoquinolines: Preparation of hydroxyisoquinolines
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A complex phenomenon was observed in the process of preparing hydroxyisoquinoline through copper-catalyzed hydrolysis of bromoisoquinoline. The copper (II) complexes of hydroxyisoquinoline (L2Cu.5H2O) were characterized by high resolution mass spectra, thermogravimetric analysis, IR, 1H nuclear magnetic resonance (NMR), and 2D-NMR. The Cu (II) complexes were mononuclear and coordinated with oxygen and nitrogen atom of two hydroxyisoquinoline and five water molecules in which a strong hydrogen bond was present. Two optimized methods had been studied to prevent the formation of copper (II) complexes. The isoquinoline with 4, 5, 6, 7, and 8 hydroxyl substitutions were successfully prepared by copper-catalyzed hydrolysis of corresponding bromoisoquinoline and then workup by sodium sulfide or adjusted pH by dry ice or carbon dioxide gas.
- Xingjun, Jiang,Jianbo, He,Hongli, Chen,Weiqing, Yang,Yuanyuan, Zhang,Menglin, Ma
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- Palladium-catalyzed enolate arylation as a key C-C bond-forming reaction for the synthesis of isoquinolines
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The palladium-catalyzed coupling of an enolate with an ortho-functionalized aryl halide (an α-arylation) furnishes a protected 1,5-dicarbonyl moiety that can be cyclized to an isoquinoline with a source of ammonia. This fully regioselective synthetic route tolerates a wide range of substituents, including those that give rise to the traditionally difficult to access electron-deficient isoquinoline skeletons. These two synthetic operations can be combined to give a three-component, one-pot isoquinoline synthesis. Alternatively, cyclization of the intermediates with hydroxylamine hydrochloride engenders direct access to isoquinoline N-oxides; and cyclization with methylamine, gives isoquinolinium salts. Significant diversity is available in the substituents at the C4 position in four-component, one-pot couplings, by either trapping the in situ intermediate after α-arylation with carbon or heteroatom-based electrophiles, or by performing an α,α-heterodiarylation to install aryl groups at this position. The α-arylation of nitrile and ester enolates gives access to 3-amino and 3-hydroxyisoquinolines and the α-arylation of tert-butyl cyanoacetate followed by electrophile trapping, decarboxylation and cyclization, C4-functionalized 3-aminoisoquinolines. An oxime directing group can be used to direct a C-H functionalization/bromination, which allows monofunctionalized rather than difunctionalized aryl precursors to be brought through this synthetic route.
- Pilgrim, Ben S.,Gatland, Alice E.,Esteves, Carlos H. A.,McTernan, Charlie T.,Jones, Geraint R.,Tatton, Matthew R.,Procopiou, Panayiotis A.,Donohoe, Timothy J.
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p. 1065 - 1090
(2016/01/15)
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- Superacidic activation of 1- and 3-isoquinolinols and their electrophilic reactions
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Isomeric 1- and 3-isoquinolinols (11 and 12) when activated in CF3SO3H-SbF5 acid system undergo selective ionic hydrogenation with cyclohexane to give 5,6,7,8-tetrahydro-1(2H)- and 5,6,7,8-tetrahydro-3(2H)-isoquinolinones (22 and 27). Under the influence of aluminum chloride similar products were also obtained along with 3,4-dihydro-1(2H)- and 1,4-dihydro-3(2H)-isoquinolinones (23 and 28), respectively. Compounds 11 and 12 also condense with benzene in the presence of aluminum halides, under mild conditions, to give 3,4-dihydro-3-phenyl-1(2H)- and 1,4-dihydro-1-phenyl-3(2H)-isoquinolinones (24 and 29), respectively. Prolonged reaction time or catalysis under strongly acidic HBr-AlBr3 provides an alternative reaction pathway to yield 5,6-dihydro-6,8-diphenyl-1(2H)- and 5,6,7,8-tetrahydro-6,8-diphenyl-3(2H)-isoquinolinones (25 and 30), respectively. Products 24 and 29 were also found to revert back to 11 and 12 in the presence of aluminum halides in o-dichlorobenzene. The mechanism of these intriguing reactions, which involves superelectrophilic dicationic intermediates, is discussed.
- Koltunov, Konstantin Yu.,Prakash, G. K. Surya,Rasul, Golam,Olah, George A.
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p. 8943 - 8951
(2007/10/03)
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- Theoretical Description of Solvent Effects. V. The Medium Influence on the Lactim-Lactam Tautomerism of Hydroxyazines
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Der Loesungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen- und der Reaktionsfeldtheorie berechnet.In Uebereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform.Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser geeignet.
- Krebs, C.,Foerster, W.,Weiss, C.,Hofmann, H.-J.
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p. 369 - 378
(2007/10/02)
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- Process for the preparation of 2H-3-isoquinolones
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A process for the preparation of 2H-3-isoquinolones having the formula SPC1 Wherein R1 and R2 are each hydrogen, halogen, lower alkyl, lower alkoxy, aryl, haloaryl, alkylaryl or alkoxyaryl; R3 and R4 are each hydrogen, lower alkyl, lower alkoxyalkyl, lower alkenyl, lower alkynyl, cycloalkyl, aryl, aralkyl, or halo-aralkyl, which comprises cyclizing an N-formyl-2-phenyl-acetamide of the formula SPC2 Wherein R1, R2, R3 and R4 have the same meaning as above, with a cyclodehydration agent. Said 2H-3-isoquinolones are useful as starting materials e.g. in the synthesis of 1,4-dihydro-1,4-etheno-isoquinolin-3(2H)-ones which are valuable chemotherapeutic agents in the treatment of disorders of the central nervous system, such as troubles of wakefulness, disorders of equilibrium and vertigo.
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