Novel Cyclyne via Mild Reductive Aromatization

Significance

A novel pyridine-containing cyclo­trimer was synthesized using a mild tin-mediated reductive aromatization as the key step in the formation of the completely conjugated, strained macrocycle. Direct cross-coupling of the para-phenyleneacetylene segments did not yield the desired macrocycle because of excessive ring strain. Attempting a sequential synthesis of the macrocycle 1 only improved the yield to 13%. The reductive aromatization of 1 to 2 was found to be very efficient (89% yield).