Synthesis of bent [4]phenylene (cyclobuta[1,2-a:3,4-b′]bisbiphenylene) and structure of a bis(trimethylsilyl) derivative: the last [4]phenylene isomer†
Abstract
The syntheses of the title compounds were accomplished by cobalt-catalyzed alkyne cyclotrimerizations using two strategies; the properties of the bent phenylene frame reflect the combined effects of benzocyclobutadienofusion of the component [3]phenylene substructures.