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

Palladium/(4-MeO-3,5-MePh)2PF-Pcy2) 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 α-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)2PF-Pcy2) complex and results of DFT computational
studies on mechanistic aspects of the catalytic cycle.