Three-Component [2+2+1] Cross-cyclotrimerization of Carboryne, Unactivated Alkene, and Trimethylsilylalkyne Co-mediated by Zr and Ni

A three-component
[2+2+1] cross-cyclotrimerization of carboryne, alkene, and trimethylsilylalkyne
has been achieved under the cooperative action of zirconium and nickel,
leading to the synthesis of a series of dihydrofulvenocarboranes.
The bulkiness of the alkyne and phosphine ligand plays a key role
in the selective formation of the products.