Novel α-fluorinated cyclic phosphite and phosphinite ligands and their Rh-complexes as suitable catalysts in hydroformylation

Asymmetrical cyclic phosphite and phosphinite ligands of a novel type bearing either trifluoromethyl or pentafluorophenyl group were synthesized using >PCl or >PN< species and racemic fluorinated alcohols. The P-ligands were converted to complexes of RhIII(L)(Cp∗)Cl2 type (where L = phosphite or phosphinite) and, in two instances, their stereostructures were evaluated by X-ray analysis. These complexes along with in situ systems, formed from Rh(CO)2(acac) precursor and the corresponding ligand, were tested in the hydroformylation of styrene. Both systems provided excellent hydroformylation activities at 100 °C. Using the RhI in situ systems, moderate and high regioselectivities towards the branched aldehyde (2-phenyl-propanal) were obtained at 100 and 40 °C, respectively.

Benzoanellated cyclic phosphite (1) and phosphinite (5) ligands with fluorine containing substituents were synthesized and converted to RhIII(L)(Cp∗)Cl2 complexes (4 and 6, respectively, where L = 1 and 5). In two cases their stereostructures were evaluated. The enantiomers of complex 6a were separated by spontaneous resolution. The complexes (4 and 6) were tested in the hydroformylation of styrene. In situ systems formed from RhI(CO)2(acac) precursor and the above P-ligands were also investigated and were found to be more efficient than the preformed ones.Figure optionsDownload as PowerPoint slide