Facile Synthesis and Global Aromaticity of Aza-Superbenzene and Aza-Supernaphthalene at Different Oxidation States.

Autor: Ma Y; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore., Han Y; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore., Hou X; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore., Wu S; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore., Chi C; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Oct 24; Vol. 63 (44), pp. e202407990. Date of Electronic Publication: 2024 Aug 13.
DOI: 10.1002/anie.202407990
Abstrakt: All-benzenoid polycyclic aromatic hydrocarbons or macrocycles usually display localized aromaticity. On the other hand, incorporation of quinoidal units into the skeleton could lead to effective electron delocalization and global (anti)aromaticity. In this work, fully π-conjugated macrocycle 1 and bismacrocycle 2 containing both para-quinodimethane and triphenylamine units are efficiently synthesized mainly through intermolecular Friedel-Crafts alkylation reaction. They can be considered as a tetraazasuperbenzene and a hexaazasupernaphthalene, respectively, due to their similar geometry and electronic structures to the benzene and naphthalene. X-ray crystallographic analyses reveal a largely planar geometry for both 1 and 2 and variable-temperature NMR measurements disclose slow dynamic processes owing to restricted ring flipping of the phenyl rings. 1 and 2 can be easily oxidized into higher-oxidation-state species. NMR and theoretical calculations indicate that 1 2+ and 1 4+ show global anti-aromaticity and aromaticity, respectively, with a dominant 32π and 30π conjugation pathway, while for the bismacrocycle 2, its dication 2 2+ , tetracation 2 4+ and hexacation 2 6+ exhibit global aromaticity, antiaromaticity, and aromaticity with a 54π, 52π and 50π conjugation pathway along the outermost backbone, respectively.
(© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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