Abstract

The Scholl reaction is a powerful method to synthesize polycyclic aromatics enabling oxidative aryl−aryl coupling without requiring prefunctionalization of the aryl groups and allowing multiple carbon−carbon bonds to be formed in one synthetic operation. Six-membered carbocycles are commonly formed in Scholl reactions, while direct formation of five-, seven-, or eight-membered rings, particularly in a predictable manner, is still unusual.1 This presentation describes a newly developed method to form an eight-membered ring in tetraphenylene derivatives by a regioselective Scholl reaction of quaterphenyl derivatives. It is found that this reaction requires the two terminal aryl groups in the quaterphenyl substrate to be much electron-richer than the two internal arylene groups, and a radical cation mechanism is proposed for this Scholl reaction on the basis of experimental results and DFT calculations.

Reference:

1. Zhang, Y.; Pun, S.; Miao, Q. Chem. Rev. 2022, published online, https://doi.org/10.1021/acs.chemrev.2c00186