Synfacts 2018; 14(09): 0919
DOI: 10.1055/s-0037-1610621
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

Polycyclic Aromatic Hydrocarbon with Embedded Azulene Unit

Timothy M. Swager
Monika Stolar
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Publication History

Publication Date:
20 August 2018 (online)



Incorporation of heptagons and pentagons into a polycyclic aromatic hydrocarbon (PAH) core leads to changes in the molecular ­geometry and electronic properties of the original PAH. This report demonstrates the use of silver(I) cations to achieve an efficient synthesis of an azulene-embedded PAH 2, which is a challenging issue that is plagued by limited methodologies.



Two-electron oxidation of the silver(I) ion promoted a three-fold transannulation reaction between the aromatic and acetylene units of 1 resulting in the selectively embedded azulenium cation 2H+ , which could be subsequently deprotonated by trimethylamine to afford the neutral azulene-embedded PAH 2. Compound 2 exhibited a low-energy absorption band featuring characteristics of the non-alternant moiety, along with reversible one-electron redox events for the oxidation or reduction of 2, resulting in tropylium cation or cyclopentadienyl anion scaffolds, respectively.