Use of thieno[2,3-b]thiophene in the synthesis of heterohelicenes by double photocyclizations

Dopper, J. H.; Oudman, D.; Wynberg, Hans

doi:10.1021/ja00792a037

Cited by 55 publications

(15 citation statements)

References 2 publications

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“…44 Somewhat later, Wynberg and Dopper 1 reported the synthesis of the first thiacirculene 13 from the corresponding hexahelicene using an original procedure through the intermediate formation of dehydrohelicene (Scheme 2). 1,49 Molecules 7 and 8 are unstrained and perfectly planar, as evidenced by X-ray diffraction data. 25 ± 27 This is in complete agreement with Wynberg ± Dopper's model (S sect = 30864+60864 = 3608).…”

Section: Ii2 Heterocyclic Circulenesmentioning

confidence: 91%

“…Dehydrohelicenes should be considered as the first synthesized heterocyclic quasicirculenes. 34,49,121,122 The synthesis of these compounds is based on the intramolecular cyclization of the corresponding heterohelicenes, 120 and they are the starting compounds in the synthesis of thia [7]circulenes. More recently, dehydrohelicenes 39 and 40 containing the inner eight-membered core 35,123 Figure 10.…”

Section: V2 Nmr and Epr Spectroscopic Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Electronic structure, aromaticity and spectra of hetero[8]circulenes

Baryshnikov¹,

Минаев²,

Минаева³

2015

Russ. Chem. Rev.

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Section: Ii2 Heterocyclic Circulenesmentioning

confidence: 91%

Section: V2 Nmr and Epr Spectroscopic Studiesmentioning

confidence: 99%

Electronic structure, aromaticity and spectra of hetero[8]circulenes

Baryshnikov¹,

Минаев²,

Минаева³

2015

Russ. Chem. Rev.

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“…In this article, we describe the unprecedented twisted nature of quadruple helicenes as a new milestone of twisted π systems. The arrangement of dithia[6]helicene and [5]helicene substructures around a naphthalene core generates 4-fold helical π systems (Figure ). Because of the proper accumulation of repulsions on helical substructures, the most severely twisted benzene rings of up to 35° as well as a naphthalene core near 70° were achieved as a saddle-shaped isomer.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Features of Quadruple Helicenes: Highly Distorted π Systems Enabled by Accumulation of Helical Repulsions

2016

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Quadruple helicenes, bearing dithia[6]helicene and [5]helicene substructures, were prepared by a well-controlled Scholl reaction. The 4-fold helicity provides 9 stereoisomers including 4 pairs of enantiomers and 1 meso isomer. Among them, differently distorted structures of a propeller-shaped isomer (QH-A) and a saddle-shaped isomer (QH-B) were unambiguously determined by X-ray crystallography. Especially in the latter isomer, a proper accumulation of repulsions on the helical substructures twisted the naphthalene core to the limit (69.5°), the highest degree of twisting deformation per benzene unit (35.3° at the most). Photophysical and electrochemical studies showed a broadened HOMO-LUMO gap and a HOMO of QH-B lying lower compared to those of QH-A. These results together with the density functional theory (DFT) calculations have clearly demonstrated the electronic state dependency on the molecular geometry. Additionally, kinetic studies of the isomerization between these isomers using (1)H NMR, circular dichroism, and DFT calculations shed light on the interconversion pathways among the stereoisomers. The height of barriers in the inversion of a certain helical substructure may be affected by the neighboring helical substructures.

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“…[21] Actually, there have been a variety of thiophene-based helicenes so far. [1,22] A. Rajca et al reported the synthesis and characterization of a thia[7]helicene 8 ( Figure 2, Table 2).…”

Section: Cation Radicals Of Helicenesmentioning

confidence: 99%

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

2020

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Chiral helicenes that have helical π-conjugated frameworks comprised of ortho-fused aromatic rings have been intensively investigated for several decades owing to their attractive properties and high potential for a variety of applications. In contrast, studies concerning helicene radicals (open-shell helicenes) formed by redox reactions have been severely limited due to inherent high reactivity of organic radicals. However, open-shell helicenes possessing a combination of chirality and unpaired electron spin(s) delocalized on helical π-conjugated orbital(s) are promising for novel synergic magnetic functions. Recently, several kinds of isolable air-stable helicene radicals have been prepared to enable their detailed analysis of the crystal structures and physicochemical properties. This Minireview describes the recent advances and future prospects of organic-based helicene radicals categorized into three groups: 1) ionic radicals, 2) neutral radicals, and 3) diradicals.

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Use of thieno[2,3-b]thiophene in the synthesis of heterohelicenes by double photocyclizations

Cited by 55 publications

References 2 publications

Electronic structure, aromaticity and spectra of hetero[8]circulenes

Electronic structure, aromaticity and spectra of hetero[8]circulenes

Synthesis and Structural Features of Quadruple Helicenes: Highly Distorted π Systems Enabled by Accumulation of Helical Repulsions

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

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