Reductive Cyclization of Diynes and Enynes Catalyzed by Allyl Platinum N-Heterocyclic Carbene Complexes

Platinum N-heterocyclic carbene (NHC) complexes have been synthesized and used as precatalysts in the reductive cyclization of diynes and eynes. 2,5-Dihydrofurans, -pyrroles, and -cyclopentenes were obtained as reductive cyclization products from oxygen-, nitrogen-, and carbon-tethered substrates, respectively. The yield and product of the reaction were highly dependent upon the substrate and the substituent on the alkyne.