C-H Activation Directed Multicomponent Assembly of Macrocycles

Significance

The authors demonstrate the synthesis of several novel organoiridium macrocycles utilizing a C-H activation directed self-assembly approach. Mixing pyrazine-bridged dinuclear iridium complex 1 with silver triflate and terephthal ­bisimines 2a-d, the corresponding tetranuclear macrocycles 3a-d could be obtained. The formation of the cyclometalated iridium corners was confirmed by X-ray structural analysis. Larger ­organoiridium ring systems (6a-b) could also be prepared by reacting 1 with N,N′-bisbenzylidene-benzene-1,4-diamines 5a-b. Further functionalization of the smaller macrocycles 3a-d was shown to be possible via the reaction of the tetranuclear complexes with the alkyne DMAD. A single alkyne insertion in each iridium-aryl bond was observed.