The Suzuki Reaction Revised – Simplification and Scale up in the Microwave Field

Metal-catalysed reactions are ubiquitous in organic chemistry and represent a modern research area. In the last years considerable progress was achieved in the field of palladium-catalysed C-Ccoupling. A high number of publications as well as a great amount of reviews and books documented the progress and is reflected in reactions names after Heck, Sonogashira, Stille or Suzuki. Reactions of this type should reach high importance in case of technical und economical feasibility in the production of fine chemicals, pharmaceuticals and other high-level products. Also microwave irradiation was used for the activation of palladium-catalysed reactions. But only in a few cases deviations from the original composition of the reaction mixture are described. These reaction mixtures are very complex in the most of the described experiments. Depending on the type of reaction the starting material (e.g. aryl halide) is reacted with a substituent-supplying educt (e. g. olefins, acetylenes, boronic acids, and siloxan derivates). However, further auxiliaries are necessary to adjust the reaction conditions. As a rule a base (e. g. triethyl amine, sodium carbonate), a metal compound (e. g. palladium acetate) and an additional complexing agent (e. g. triphenyl phosphine) are required beside a solvent (often DMF). The described reaction times are often very long, when the reaction is carried out at room temperature or slightly above. The resulting mixtures are worked up in the most cases by diluting with water and extraction a water immiscible organic solvent (MTBE, dichloromethane). We discuss here two concepts for the simplification of the Suzuki reaction, in which the entry of microwave energy plays important role in the reaction processing. Scale-up is also taken into consideration. Preliminary results are represented her.