Totally chemo- and regioselective cobalt(I)-mediated formal intermolecular cyclotrimerization of alkynes

The first examples of totally chemo- and regioselective formal intermolecular cobalt(I)-catalyzed [2 + 2 + 2] cyclizations of three different alkynes are reported. The use of disposable silylated tethers in the sequence cyclization followed by the displacement of the silicon group led to polysubstituted arenes as a unique cycloadduct in high yields.