Azaarenes: 13 Rings in a Row by Cyclopentannulation

Abstract

Cyclopentannulation was explored as a strategy to access large, stable azaarenes. Buchwald-Hartwig coupling of previously reported di-and tetrabrominated cyclopentannulated N,N'-dihydrotetraazapentacenes furnished stable azaarenes with up to 13 six-membered rings in a row and a length of 3.1 nm. Their optoelectronic and semi-conducting properties as well as their aromaticity were investigated.

Pyridinic Nitrogen Doping: A Versatile Approach for Precise Structure–Property Manipulations of Nanographenes

“…(c) AICD-π-only plot of 32 (B3LYP/def2TZVP). Reproduced with permission under a Creative Commons [CC-BY 3.0] license from ref . Copyright 2023 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.…”

“…In 2022, Bunz et al successively prepared a set of large but stable cyclopentannulated tetraazaacenes ( 29 – 32 ), consisting of 5, 9, 11, and 13 six-membered rings in a row, respectively (Figure a). − The key tetrabrominated pentannulated dihydrotetraazapentacenes were first synthesized through a palladium-catalyzed 5-endo-dig cyclization from TIPS-ethynylated dihydrotetraazapentacene. Whereafter, the desired target products were afforded with reasonable yields via the widely used Buchwald–Hartwig coupling reactions with diaminoarenes and subsequently MnO 2 -mediated oxidative dehydrogenation reactions.…”

Molecular engineering of 3-arylated tetrazo[1,2-b]indazoles: divergent synthesis and structure–property relationships

“…1 Nitrogen-containing heteroaromatics, including among many others pyrazino[2,3- b :5,6- b ′]diindolizines ( A , Scheme 1) and azapyridazines ( B , Scheme 1) have been developed for applications in optoelectronics or bioimaging. 2 However, in this field, the development of efficient synthetic approaches for innovative building blocks remains highly desirable, notably for safety and more atom-economy reasons. In this context, we have recently developed an unprecedented synthesis of tetrazo[1,2- b ]indazoles (TzIn, C and D , Scheme 1) through the N–N cyclization of azido-functionalized s -tetrazines (Scheme 1, bottom).…”