Toward the Synthesis of a Belt-Shaped Cyclic π-Conjugated System Comprising para-Phenylene Framework and Amide Bridging Unit

Abstract

Abstract Belt-shaped π-conjugated systems have been attracting more and more attention in recent years from the synthetic interest as well as their mysterious properties that linear counterparts do not have. In this paper, the stepwise condensation of 2-bromo-4-(octylamino)benzoic acid and subsequent macrocyclization was carried out to obtain a cyclic hexamer (c6mer). The palladium-catalyzed direct arylation was then performed to get the target belt-shaped molecule (b6mer) although the isolation of b6mer did not meet with success because of the contamination of structural defects. Theoretical calculation of b6mer indicated the strain energy of ca. 100.9 kcal·mol−1 and revealed the electronic transition from degenerate HOMO-1 and HOMO-2 orbitals to LUMO similar to that of parent cycloparaphenylene derivatives.