Mild Palladium-Catalyzed Cyanation of (Hetero)aryl Halides and Triflates in Aqueous Media-

Reaction Scheme

Abstract

The development of a novel Pd-catalyzed synthesis of (hetero)aromatic nitriles from the corresponding aryl chlorides and potassium hexacyanoferrate(II) is described. This novel protocol avoids the use of highly toxic alkali cyanides and proceeds in the presence of small amounts of palladium catalysts. High yields and selectivities of the corresponding aryl nitriles were achieved applying di(1-adamantyl)-1-butylphosphine (cataCXium�A) as the ligand.

Substrates

Procedure

Potassium hexacyanoferrate(II) (0.4�mmol) (either powdered K4[Fe(CN)6]?3H2O or dry K4[Fe(CN)6], which is yielded by grinding K4[Fe(CN)6]?3H2O to a fine powder and drying in vacuum (ca. 2�mbar) at 80��C overnight), 2�mmol aryl chloride, 0.4�mmol Na2CO3, metal precursor and ligand (in a stock solution in the given solvent) are mixed in a pressure tube under argon. Then the solvent (filled up to 2�ml) and 200�?l of internal standard (tetradecane) are added and the mixture is stirred for 16�h at the given temperature. After cooling to room temperature, 3�ml of dichloromethane are added and the reaction mixture is analyzed by GC. Conversion and yield are calculated as average of 2 parallel runs. The products can be isolated by column chromatography (SiO2, ethyl acetate/hexane) after washing the organic phase with water, drying over sodium sulfate and distilling the solvents.

Products

Materials

     
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