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

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.