Abstract: A palladium-catalysed carbon-carbon bond forming reaction in compressed carbon dioxide is provided wherein at least one of the reagents used in said reaction is bounded to a solid polymer support. In a second aspect, a palladium-catalysed carbon-carbon bond forming reaction in compressed carbon dioxide is provided wherein said reaction is performed in the presence of a tetra-alkylammonium acetate. In a third aspect, a palladium-catalysed carbon-carbon bond forming reaction in compressed carbon dioxide is provided wherein said palladium catalyst does not have any fluorinated phosphine ligands but does have at least one phosphine ligand that has at least one substituent that is selected from tert-alkyl groups, cycloalkyl groups and optionally substituted phenyl groups or 1?-diphenylphosphino-biphenyl. In a fourth aspect, there is provided a palladium-catalysed Suzuki or Heck reaction in compressed carbon dioxide wherein both of the substrates being combined in said reactions are boronic acids.

Abstract: There is provided processes for metal mediated reactions, particularly cross coupling and carbometallation reactions, wherein the metal is present as a catalyst system comprising a catalyst microencapsulated within a permeable polymer microcapsule shell and the reaction is carried out under super-critical or near super-critical conditions. Preferred metal-mediated cross coupling reactions include Heck, Suzuki, Sonogashira and Stille reactions. Preferred carbometallation reactions include hydroformylations.