One‐Pot Synthesis of Helical Azaheptalene and Chiroptical Switching of an Isolable Radical Cation

A nitrogen‐centered heptalene, azaheptalene, was designed as a representative of a new class of redox‐responsive molecules with a large steric strain that originates from the adjacent seven‐membered rings. The pentabenzo derivative of azaheptalene was efficiently synthesized by a palladium‐catalyzed...

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Published inChemistry : a European journal Vol. 29; no. 48; pp. e202301759 - n/a
Main Authors Nishimura, Yuta, Harimoto, Takashi, Suzuki, Takanori, Ishigaki, Yusuke
Format Journal Article
LanguageEnglish
Published WEINHEIM Wiley 25.08.2023
Wiley Subscription Services, Inc
Subjects
azaheptalene
Bromination
Cations
Chemical synthesis
Chemistry
Chemistry, Multidisciplinary
chiroptical response
Electric potential
Enantiomers
Helicity
Infrared absorption
Near infrared radiation
Palladium
Physical Sciences
radicals
Reagents
Science & Technology
chiroptical response
azaheptalene
cations
helicity
radicals
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Summary:A nitrogen‐centered heptalene, azaheptalene, was designed as a representative of a new class of redox‐responsive molecules with a large steric strain that originates from the adjacent seven‐membered rings. The pentabenzo derivative of azaheptalene was efficiently synthesized by a palladium‐catalyzed one‐pot reaction of commercially available reagents. Bromination led to mono‐ and dibrominated derivatives, the latter of which is interconvertible with isolable radical cation species exhibiting near‐infrared absorption. Since the azaheptalene skeleton shows configurationally stable helicity with a large torsion angle, enantiomers could be successfully separated. Thus, optically pure azaheptalenes with P‐ or M‐helicity showed strong chiroptical properties (|gabs|≥0.01), which could be changed by an electric potential. A N‐centered helical heptalene, azaheptalene, was synthesized by a palladium‐catalyzed one‐pot reaction. Since the azaheptalene skeleton shows configurationally stable helicity, enantiomers could be successfully separated. Moreover, thanks to the electron‐donating N atom, such helical azaheptalene with two bromine atoms undergoes one‐electron oxidation to produce radical cation species with a drastic chiroptical response.
Bibliography:https://doi.org/10.26434/chemrxiv‐2023‐sc6tf
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A previous version of this manuscript has been deposited on a preprint server
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content type line 23
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.202301759