[(NHC)(NiH)-H-II]-Catalyzed Cross-Hydroalkenylation of Cyclopropenes with Alkynes: Cyclopentadiene Synthesis by [(NHC)Ni-II]-Assisted C-C Rearrangement

A cross-hydroalkenylation/rearrangement cascade (HARC), using a cyclopropene and alkyne as substrate pairs, was achieved for the first time by using new [(NHC) Ni(allyl)]BArF catalysts (NHC=N-heterocyclic carbenes). By controlling the (NHC) (NiH)-H-II relative insertion reactivity with cyclopropene and alkyne, a broad scope of cyclopentadienes was obtained with highly selectively. The structural features of the new (NHC)Ni-II catalyst were important for the success of the reaction. The mild reaction conditions employed may serve as an entry for exploring (NHC)Ni-II-assisted vinylcyclopropane rearrangement reactivity.