24-08434SR - Short Report J. Braz. Chem. Soc. , Vol. 20,...

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Unformatted text preview: Short Report J. Braz. Chem. Soc. , Vol. 20, No. 5, 988-992, 2009. Printed in Brazil - 2009 Sociedade Brasileira de Qumica 0103 - 5053 $6.00+0.00 *e-mail: hstefani@usp.br; dsalves@gmail.com Copper Catalyzed Cross-Coupling Reactions of Diaryl Ditellurides with Potassium Aryltrifluoroborate Salts Diego Alves,* ,a Jesus M. Pena, a Adriano S. Vieira, a Giancarlo V. Botteselle, a Rafael C. Guadagnin a and Hlio A. Stefani* ,a,b a Departamento de Farmcia, Faculdade de Cincias Farmacuticas, Universidade de So Paulo, 05508-900 So Paulo-SP, Brazil b Departamento de Biofsica, Universidade Federal de So Paulo, 04023-062 So Paulo-SP, Brazil Apresentamos aqui resultados das reaes de acoplamento de diteluretos de diarila com sais de ariltrifluoroborato de potssio, usando quantidades catalticas de Cu(OAc) 2 e bipiridina, em uma mistura de DMSO/H 2 O, sob ar atmosfrico. Estas reaes de acoplamento so gerais e so realizadas com diteluretos de diarila e sais de ariltrifluoroborato de potssio contendo substituintes neutros, retiradores e doadores de eltrons, fornecendo os correspondentes teluretos de diarila no simtricos em rendimentos de bons a excelentes. We present here results of the cross-coupling reaction of diaryl ditellurides with potassium aryltrifluoroborate salts using a catalytic amount of Cu(OAc) 2 and bypiridine in DMSO/H 2 O under air atmosphere. This cross-coupling reaction is general and was performed with diaryl ditellurides and potassium aryltrifluoroborate salts bearing electron-withdrawing, electron-donating and neutral substituents, affording the corresponding unsymmetrical diaryl tellurides in good to excellent yields. Keywords: tellurium, trifluoroborate salts, copper catalysis Introduction Chalcogenide compounds have become attractive synthetic targets because of their chemo-, regio-, and stereoselective reactions, 1-4 used in a wide variety of functional groups, thus avoiding protection group chemistry and resulting in useful biological activities. 5-7 Therefore, many classes of organotellurium compounds have been prepared and studied to date and aryl- or vinylic tellurides are certainly the most useful and promising compounds in view of their usefulness in organic synthesis. 8-11 A large number of methodologies have been reported to prepare these compounds. 4,9-11 However, limited synthetic methods are reported to synthesize unsymmetrical diaryl tellurides. In recent years, a transition-metal-catalyzed reaction of diaryl dichalcogenides with aryl halides or boronic acids has become a versatile tool for synthesis of unsymmetrical diaryl chalcogenides. 12-17 Recently, Taniguchi 12 described the preparation of numerous unsymmetrical organotellurides by reaction of organoboronic acids with ditellurides via cleavage of Te-Te bond by a copper catalyst....
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24-08434SR - Short Report J. Braz. Chem. Soc. , Vol. 20,...

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