Synthesizing Strained Azatriseptane Frameworks

Abstract

Embedding seven-membered rings into polycyclic aromatic molecules is attractive as they can exert an influence on molecular conformation that ultimately changes the solubility and π-electronics. The considerations in designing and synthesizing a highly strained azatriseptane framework is discussed herein. We employ a twofold macrocyclization strategy to form the [7,7,7]-system and through scoping various strategies identify a Friedel-Crafts approach is key. The synthetic limitations we have identified, in addition to the successes presented here, highlights the key challenges in forming triseptane frameworks and paves the way for secondgeneration analogues that may have various applications in optical as well as electronic organic materials.

Synthesis of Polycyclic Aromatic Hydrocarbons with Highly Twisted N-Doped Heptalene

“…For example, Rickhaus et al reported the synthesis of dibenzo-azabenzo[ef]heptalene derivatives in the pursuit of azatriseptane. 15 During the preparation of this manuscript, azaheptalene 2 was reported by Ishigaki et al via a one-pot method, and its chiral property was investigated. 16 Herein, we report the synthesis of a series of π-extended PAHs with N-doped heptalene or N-doped azulene, respectively, which can be viewed as benzannulated I and II, via a different synthetic strategy.…”

Synthesis, Structure, and Properties of a Nitrogen–Boron–Nitrogen-Embedded Polycyclic π-System Containing a Pleiaheptalene Framework

“…Unfortunately, extended π-systems based on a pleiaheptalene framework have not been achieved, possibly due to synthetic challenges. 12 In this work, electrophilic borylation is used to construct the NBN unit, and the three-fused heptagon system is successfully formed meanwhile. The structure of 1 was unambiguously confirmed by X-ray diffraction analysis and further compared to its structure motif-pleiaheptalene.…”

“…Pleiaheptalene was first reported in 1986 by Hafner et al; it adopts a saddle shaped conformation with an interesting dynamic process. Unfortunately, extended π-systems based on a pleiaheptalene framework have not been achieved, possibly due to synthetic challenges . In this work, electrophilic borylation is used to construct the NBN unit, and the three-fused heptagon system is successfully formed meanwhile.…”