Platinum(II) Catalysts for Highly Enantioselective 1,6-Enyne Cycloisomerizations. Synthetic, Structural, and Catalytic Studies

A new family of cyclometalated (N-heterocyclic carbene)Pt-II complexes bearing monodentate phosphines as ancillary ligands has been designed for use as precatalysts in 1,6-enyne cycloisomerization reactions. Highly enantioselective skeletal rearrangements of allylpropargyl-tosylamide derivatives have been developed by using (S)-Ph-Binepine as the chiral auxiliary. Enantiomeric excesses up to 97% have been obtained.