Synthesis of flexible, fluorous 'ponytail' modified triarylphosphines for utilization in fluorous biphase systems

The synthesis of several triarylphosphines incorporating poly(hexafluoropropylene oxide) [pHFPO] is presented. Hydrogenation of 2-cyclohexen-1-one using a fluorinated Wilkinson’s catalyst analogue prepared from one of these ligands was investigated under fluorous biphasic conditions. A 0.5 % catalyst load was recycled through 6 cycles by exploiting the facile catalyst recovery afforded by the thermoregulated miscibility of the perfluorinated solvent with normal organic solvents. Catalytic performance was examined under biphasic as well as monophasic conditions using tris(4-diphenylphosphino) pHFPO methylene benzoate rhodium chloride, a fluorous analogue of Wilkinson’s catalyst. The partitioning behavior was analyzed for the free ligand, ligand oxide and rhodium-bound ligand. This represents the first example of a polyhexafluoropropylene oxide-modified triarylphosphine-based catalyst.