Front Cover Picture: A 6π Azaelectrocyclization Strategy towards the 1,5,9‐Triazacoronenes (Adv. Synth. Catal. 8/2020)

Abstract

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).

Trivalent Phosphine‐Catalyzed Reactions Using Fluorinated Building Blocks

“…[3+2] Annulation predominated from N ‐alkylated substrates, whereas [4+2] annulation of N ‐sulfonyl materials predominated to give trifluoromethylated O ‐bridged benzoazepine 154 or 155 derivatives, respectively (Scheme 27). [76] The reaction is initiated by generating the zwitterionic intermediate 156 from 109 and P(4‐FC 6 H 4 ) 3 , which attacks the carbonyl group of 117 b / 117 c to afford vinyl phosphonium species 157 a / 157 b . The more acidity of N− H in N ‐sulfonated substrates makes the deprotonation much easier than that of the N ‐benzyl substrates.…”