Transition-metal catalyzed [2 + 2 + 2] cyclotrimerizations of alkynes has been recognized as a straightforward route to substituted benzenes. 1 The control of both the chemo- and regio-chemistries in the cyclotrimerization of two or three different alkyne components, however, have been a crucial problem. Although the selective cyclocotrimerization of three different alkynes was achieved using stoichiometric zirconocene reagent, 2 the regiochemistry problem has remained ...
