We present the instance of two aromatic double bonds and an imine double bond involved thermal 6π-azaelectrocyclization and, on this basis, a one-step synthesis of triazacoronenes (TACs) from triphenylene-1,5,9-triamines and aldehydes under nonacidic conditions. This method has several advantages such as simplicity, high yields, and extensive substrate scope. A plausible reaction mechanism has been proposed with several experimental supports. A typical derivative shows a unique dimer holding together via a π-π interaction and six H-bonds and a zigzag superstructure stabilized by three centered H-bonds and Br ··· π interaction between the adjacent dimers. Figure 1. Coronene and its triaza derivatives.
The front cover picture, provided by Jun‐Fa Wei et al., shows the instance of two aromatic double bonds and an imine double bond involved in a thermal 6π‐azaelectrocyclization, leading to triazacoronenes (TACs) under non‐acidic conditions. This method provides an effective complement to the previous methods and, meanwhile, represents a new synthesis tool for the TACs family. The picture depicts the synergetic cyclization process of π electrons to yield the products. Further details of this work can be found in the communication on pages 1651–1656 (Y.‐X. Sun, X.‐G. Wang, G.‐D. Shen, T. Yang, Y.‐H. Yang, J. Li, M.‐Y. Yang, H.‐M. Sun, J.‐F. Wei, Adv. Synth. Catal. 2020, 362, 1651–1656; DOI:10.1002/adsc.201901433).
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