Elektrochemisch-präparative Synthesen zur Bindungsknüpfung zwischen potentiellen Carbeniumionenbildnern und C-H-, N-H- und S-H-aciden Verbindungen

Die Elektrochemie hat in den letzten Jahren eine Reihe interessanter Synthesemethoden als Alternative zur konventionellen organischen Synthesechemie entwickelt. Die Elektrosynthese ist ein vielseitiges Mittel zur selektiven Reduktion oder Oxidation von organischen Verbindungen. Die leichte Kontrolli...

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Bibliographic Details
Main Author: Machmur, Rospita Torpikai
Contributors: Hanefeld, Wolfgang (Prof. Dr.) (Thesis advisor)
Format: Doctoral Thesis
Language:German
Published: Philipps-Universität Marburg 2006
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Because of the importance of derivatives of C-C-, C-N- and C-S-bonds in organic and medicinal chemistry, developement of new methodes for there efficient synthesis is an important challenge. The anodic oxidation is a novel and operationally simple method for the preparation of several types of compounds. We use controlled potential electrolysis for selective reaction. After separation of one proton and two electrons, carbenium-ions are obtained which react with nucleophiles in a solution of acetonitrile to yield the compounds described below. We chose xanthene, thioxanthene, diphenylmethane, triphenylmethane and 3,4-dihydro-2H-pyran as carbenium-ion-precursors and CH-, NH- and SH-acid substrates as nucleophiles. Derivatives of thioacetic acid, 2-mercaptoacetamides, 2-mercaptopropaneamides, 3-mercaptopropaneamides and bifunctional 2-mercaptopropaneamides with xanthene and thioxanthene were prepared by forming C-S-bonds. Other C-S-bonds have been built up with substituted thiophenoles and bifunctional derivatives by reaction with carbenium-ion-precursors. Reactions of methanesulfonamide, ortho-toluensulfonamide, 3,5-dinitrobenzenesulfonamide and 4-chlor-3-nitrobenzenesulfonamid as N-nucleophiles resulted in the formation of C-N-bonds. N-hydroxyacetamide, hydroxyurea, N-hydroxyurethane, tert.butyl-N-hydroxycarbamate, N-(benzylcarbonyl)hydroxylamine and benzohydroxamic acid formed via anodic oxidation C-N-derivatives. The anodic oxidation of thioxanthene in the presence of water resulted in the formation of the corresponding sulfoxides and sulfones. Diphenylmethane formed as carbenium-ion-precursor novel C-N-coupling products with 1H-benzotriazole and 4-chlor-3-nitrobenzenesulfonamide. Triphenylmethane reacted with malononitrile with C-C-bond-formation. NH-acidic substrates like benzamide and 4,5-dicyanoimidazole were used as nucleophiles in the formation of C-N-bonds. The anodic oxidation of diphenylmethane and triphenylmethane in the presence of water resulted in the formation of C-O-bonds , meaning formation of alcohols. The anodic oxidation of 3,4-dihydro-2H-pyran with nucleophiles resulted in nucleophilic addition to the double bond and not as shown in previous experiments in the formation of a carbenium ion of the substrate with following nucleophilic attack. Reactions of 6-nitroindazole, 1H-benzotriazole, benzamide, para-toluenesulfonamide and 4-nitrobenzenesulfonamide with 3,4-dihydro-2H-pyran resulted in the formation of C-N-bonds.