Synthesis of Boronate‐Based Benzo[<i>fg</i>]tetracene and Benzo[<i>hi</i>]hexacene via Demethylative Direct Borylation

Numano, Misa; Nagami, Naoto; Nakatsuka, Soichiro; Katayama, Takazumi; Nakajima, Kiichi; Tatsumi, Sou; Yasuda, Nobuhiro; Hatakeyama, Takuji

doi:10.1002/chem.201602753

Cited by 99 publications

(80 citation statements)

References 54 publications

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“…Astonishingly, the formation of 2 a still took place, albeit with Mes‐BBr 2 as the by‐product instead of mesitylene, indicating a complicated reaction mechanism. The conversion of 2 a to 2 b however was inhibited by DIPEA, supporting that the second Mes group likely acts as an intramolecular H + scavenger, in a manner similar to the previously reported reactivity of BAr 3 as an additive in FC borylations …”

Section: Methodssupporting

confidence: 85%

“…Lewis acids, for example, AlCl 3 , in combination with a bulky amine NR 3 can activate the electrophile by formation of borenium ions [R 3 N‐BX 2 ] + . Removal of the HX produced can occur through NR 3 or, most recently, through addition of triarylboranes BAr 3 . Other methods include Wacker type cyclisations, hydroboration with NHC borenium ions, and construction of the targeted PAH framework around a pre‐installed boron center via Yamamoto coupling or Scholl reactions .…”

Section: Methodsmentioning

confidence: 99%

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Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B‐Doped Benzo[4]helicenes

et al. 2020

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New symmetric and unsymmetric B,N,B‐doped benzo[4]helicenes 3–6 a/b have been achieved in good yields, using a three‐step process, starting from N(tolyl)3 in a highly divergent manner (7 examples). A borinic acid functionalized 1,4‐B,N‐anthracene 1 was found to display unprecedented reactivity, acting as a convenient and highly effective precursor for selective formation of bromo‐substituted B,N,B‐benzo[4]helicenes 2 a/2 b via intramolecular borylation and sequential B−Mes bond cleavage in the presence of BBr3. Subsequent reaction of 2 a/2 b with Ar‐Li provided a highly effective toolbox for the preparation of symmetrically/unsymmetrically functionalized B,N,B‐helicenes. Their high photoluminescence quantum yields along with the small ΔEST suggest their potential as thermally activated delayed fluorescence (TADF) emitters for organic light‐emitting diodes (OLEDs).

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Section: Methodssupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B‐Doped Benzo[4]helicenes

et al. 2020

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“…The dopingo fp olycyclic aromatic hydrocarbons (PAHs) is currently emerging as one of the most promising approaches to tailor the optoelectronic properties of organic semiconductors. [1][2][3][4] The substitution of C=Cb onds with isoelectronic and isostructural dipolar boron-nitrogen (BN) [5][6][7] andb oronoxygen (BO) [8][9][10][11] couples is an efficient method to gain control of the HOMO-LUMO bandgap withouts ignificant structural modifications of the molecular scaffold. [12,13] The use of polar BN and BO bonds typicallyw iden the HOMO-LUMO gap [14,15] and imparts dipole-driven self-assembly behaviors in the solid state [3,16] ando ns urfaces.…”

Section: Introductionmentioning

confidence: 99%

Boron–Nitrogen‐Doped Nanographenes: A Synthetic Tale from Borazine Precursors

Dosso

Battisti

Ward

et al. 2020

Chemistry A European J

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In this work, ac omprehensive account of the authors' synthetic efforts to prepareb orazino-doped hexabenzocoronenes by using the Friedel-Crafts-type electrophilic aromatic substitution is reported. Hexafluoro-functionalized aryl borazines, bearing an ortho fluoride leaving group on each of the N-and B-aryl rings,w as shown to lead to cascade-type electrophilica romatic substitution events in the stepwise CÀCbond formation, giving higher yields of borazinocoronenes than those obtained with borazine precursors bearing fluoride leavingg roups at the ortho positions of the B-aryl substituents. By using this pathway,a nu nprecedented boroxadizine-doped PAHf eaturing ag ulf-type periphery could be isolated,a nd itss tructure proven by single-crystal X-ray diffraction analysis. Mechanistic studies on the stepwise Friedel-Crafts-type cyclization suggestt hat the mechanism of the planarizationr eactionp roceeds through extension of the p system. To appraise the doping effect of the boroxadizine unit on the optoelectronic properties of topology-equivalent molecular graphenes, the all-carbon and pyrylium PAHa nalogues, all featuring ag ulf-type periphery, were also prepared. As already shown for the borazinodoped hexabenzocoronene, the replacement of the central benzene ring by its B 3 N 2 Oc ongener widens the HOMO-LUMO gap and dramaticallye nhances the fluorescence quantum yield.[a] J. Scheme1.Synthetic planarizationp rotocols for preparing borazino-doped hexabenzocoronenes 1 and 2.Figure 7. ESP surfaces mapped on the vdW surface up to an electrondensity of 0.05 electronbohr À3 for a) 11 and b) 18.Side (up) and top (bottom) view of the packingo fc )11 and d) 18.Atom colors:pink B, blue N, red O, gray C. Spacegroups: P2 1 /c and P1.

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“…One of the most powerful tools for constructing boron containing p-conjugated frameworks is electrophilicC ÀHb orylation. [7,8] In particular,i ntramolecular reactions [9,10] have afforded an umber of polycyclic aromaticc ompounds containing boron atoms with excellent optical and electronic properties.…”

mentioning

confidence: 99%

Synthesis of Tetracoordinate Boron‐Fused Benzoaceanthrylene Analogs via Tandem Electrophilic C−H Borylation

Oda

Abe

Yasuda

et al. 2019

Chemistry An Asian Journal

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Benzoaceanthrylene analogs with tetracoordinate boron at the ring junction were synthesized through tandem electrophilic CÀHb orylation of 2,6-dinaphthylpyridine followed by nucleophilic substitution. Notably,t he [5,6]-annulation occurred selectively over [6,6]-annulation with the assistance of nitrogen coordination of the pyridine ring. The X-ray crystallographic analysis revealed the polycyclic skeleton with ad istorted tetracoordinate boron atom and au nique packing structurew ith intermolecular p-p interaction. The photophysical and electrochemical properties of these benzoaceanthrylene analogs were evaluated by UV-vis spectroscopy and differential pulse voltammetry.The electron affinity of the fluorine-substituted derivative is estimated to be 3.49 eV from the ionization potentiala nd opticalb and gap. Thus, this derivative is expected to be ap romising n-type semiconducting material.

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Synthesis of Boronate‐Based Benzo[fg]tetracene and Benzo[hi]hexacene via Demethylative Direct Borylation

Cited by 99 publications

References 54 publications

Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B‐Doped Benzo[4]helicenes

Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B‐Doped Benzo[4]helicenes

Boron–Nitrogen‐Doped Nanographenes: A Synthetic Tale from Borazine Precursors

Synthesis of Tetracoordinate Boron‐Fused Benzoaceanthrylene Analogs via Tandem Electrophilic C−H Borylation

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