A new family of cyclometalated (N-heterocyclic carbene)-PtII 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
carbene‐containing metallacyclic units and monodentate chiral phosphines have been prepared. The key step of their synthesis is the intramolecular oxidative addition of N‐2‐iodobenzylimidazolylidene‐platinum(0)‐diene complexes in the presence of the chiral phosphorus ligands. The platinum(II) metallacycles have been used as well‐defined pre‐catalysts for the enantioselective cycloisomerization of nitrogen‐tethered