Pd/Josiphos-Catalyzed Enantioselective α-Arylation of Silyi Ketene Acetals and Mechanistic Studies on Transmetalation and Enantioselection

Palladium/(4-MeO-3,5-MePh)(2)PF-Pcy(2)) catalyzed the enantioselective arylation of silyl ketene acetals with iodoarenes in the presence of TlOAc to promote transmetalation of silyl ketene acetals. The highest enantioselectivities giving alpha-arylesters up to 91% ee were achieved when (E)-1-methoxy-1-(trimethylsiloxy)propene (E/Z = 88/12) was used for the silyl ketene acetal. The effect on enantioselection of a chiral ligand is discussed on the basis of the X-ray structure of the palladium/(4-MeO-3,5-MePh)(2)PF-Pcy(2)) complex and results of DFT computational studies on mechanistic aspects of the catalytic cycle.