Zirconium/nickel comediated one-pot three-component cascade cyclization of carboryne, alkene, and 2-bromophenyltrimethylsilylacetylene has been achieved, leading to the formation of a series of C,C,B-substituted carborane-fused tricyclics. On the basis of experimental results, a plausible mechanism is proposed including [2 + 2 + 1] cross-cyclotrimerization followed by intramolecular direct selective cage B-C(sp(2)) coupling. This represents the first example of direct cage B-C(phenyl) coupling via cage B-H activation.
Quan YJ,Qiu ZZ,Xie ZW. Transition-Metal-Mediated Three-Component Cascade Cyclization: Selective Cage B-C(sp(2)) Coupling of Carborane with Aromatics and Synthesis of Carborane-Fused Tricyclics[J]. J. Am. Chem. Soc.,2014,136(21):7599-7602.