Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• the field of bioconjugation and materials research. We previously reported a regioselective double addition of organic azides to octadehydrodibenzo[12]annulene derivatives with electron-rich alkyloxy substituents. In order to increase the reaction rate, electron-withdrawing substituents were

• introduced into octadehydrodibenzo[12]annulene. In this report, the synthesis of new octadehydrodibenzo[12]annulene derivatives, regioselective double addition of organic azides, and an application to crosslinking polymers are described. Keywords: annulene; click chemistry; polymerization; strain-promoted

• ], and crosslinked polymers [14][15][16][17]. Since crosslinking polymers requires high reaction efficiency under mild conditions, developing such reactions is crucial. We previously reported the regioselective double azide addition to octadehydrodibenzo[12]annulene with hexyloxy substituents (DBA-OHex

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• annulene [12], and twisted naphthalene as central spacers [19]. As its close analogue, selenophene has properties very similar to those of thiophene. Fused aromatic compounds containing selenophene units show favorable optical and electrochemical properties and improved charge transport characteristics in

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• mentioned the synthesis of dimethylmethanofullerene 6 from dimethyldiazomethane via the formation of annulene 5 according to Scheme 5 [82]. The reactions of C60 with other diazo derivatives also result in mixtures of various isomers. The ratio between the [5,6]-open fulleroid type and [6,6]-open

• mechanism of a family of fulleroids by cyclopropanation of C60 with diazo compounds. Synthesis of 1,2-methanobuckminsterfullerene 3 and related fulleroid 4. Synthesis of dimethylmethanofullerene 6 from dimethyldiazomethane via the formation of annulene 5. ODCB = orthodichlorobenzene. Synthesis of

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• concerted conrotatory process [47][48] would create a strained cis,trans-dihydrobenzo[8]annulene ring system. Cyclobutenes resulting from a [2 + 2] cycloaddition of electrophilic alkynes and alkenes under moderate thermal conditions have been isolated also from the reaction of CF3-free propyniminium salts

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

• Sergey A. Dobrynin,
• Igor A. Kirilyuk,
• Yuri V. Gatilov,
• Andrey A. Kuzhelev,
• Olesya A. Krumkacheva,
• Matvey V. Fedin,
• Michael K. Bowman and
• Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

• . These data can be obtained free of charge from The Cambridge Crystallographic Data Centre at http://www.ccdc.cam.ac.uk. Synthesis of dimethyl 2,3,3a,3b,4,5,6,7,8,9,10,11-dodecahydro-1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene-7,8-dicarboxylate (1) A mixture of ammonium acetate (616 mg, 8 mmol

• (Rint 0.0429), R1 0.0602, wR2 0.1696, S 1.030 [for 3234 I > 2σ(I)]. Synthesis of 3a-hydroxy-7,8-bis(methoxycarbonyl)-2,3,3a,3b,4,5,6,7,8,9,10,11-dodecahydro-1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene N-oxyl (6) A 70% m-CPBA solution (200 mg, 0.9 mmol) was added to a solution of amine 1 (108 mg, 0.3

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• -ATR, 1H and 13C NMR spectroscopy and elemental analysis. Keywords: crown ether; dibenzotetraaza[14]annulene; DBTAA; macrocycle; Schiff base; Introduction The design and synthesis of novel polycyclic receptor architecture is of fundamental importance, since model recognition studies contribute to

• partially overlapped with proton resonances of aliphatic bridges. Receptor 3b displays the properties of chemical shift reagents, similar to the previously reported crown ether-capped porphyrin [36] but of different origin. Since, the macrocyclic dibenzotetraaza[14]annulene core is antiaromatic, and shows

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• ) 2.1.1. Oxidation of benzo[7]annulenes: 4,5-Benzotropone (11) was synthesized for the first time via oxidation with selenium dioxide of 7H-benzo[7]annulene (14, Scheme 2) [39][40][41][42][43][44][45]. Furthermore, the direct oxidation of 5H-benzo[7]annulene to benzotropones was examined by Srivastava and

• Dev [37]. The selenium dioxide oxidation of 5H-benzo[7]annulene (15) furnished not only 4,5-benzotropone (11; 27%) but also 2,3-benzotropone (12; 13%, Scheme 2). Pomerantz and Swei [51] investigated the oxidation of benzotropylium cation 16 with several oxidants. The oxidants used and results obtained

• -benzo[7]annulene (22) with CrO3 and SeO2 as oxidation reagents were studied (Scheme 4) [52]. All reactions provided 4,5-benzotropone (11) in addition to a few benzotroponoid compounds 23–26, the structures of which were determined by means of spectral data and chemical transformations. It is deemed that

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• choice of base, leading to the construction of a [7]annulene system (Scheme 5). The use of lithium bases, such as lithium diisopropylamide and lithium hexamethyldisilazide, induced HF eliminations as well as substantial HI elimination. However, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) exclusively

• promoted HI elimination to afford ring-difluorinated dibenzo[a,c][7]annulene 7a in an almost quantitative yield. Since dibenzo[a,c][7]annulenes serve as bioactive agents, this method would be of value in the research directed toward pharmaceutical and materials chemistry [33][34][35]. Conclusion In summary

• . After removal of the solvent under reduced pressure, the residue was purified by PTLC (hexane/ethyl acetate 10:1) to give 5,5-difluoro-6-iodo-6,7-dihydro-5H-dibenzo[a,c][7]annulene (6a, 33 mg, 92%) as a colorless liquid. 1H NMR (500 MHz, CDCl3) δ 3.06 (dd, J = 14.8, 4.9, 1H), 3.38 (dd, J = 14.8, 6.0 Hz

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• indicates that the aggregation of 28, 30, and 31 is an enthalpically driven process that is entropically disfavored (Table 3) [68], although the aggregation of planar macrocyclic belts is both enthalpically and entropically driven [71]. The TTF[18]annulene 30 has smaller ΔH and ΔS values than the TTF[12

• ]annulene 28, suggesting a higher stacking ability and a larger ring size for 30. Alkyl-substituted TTF[18]annulene 32 was reported to show almost no aggregation behavior in solution [72]. However, the slightly more amphiphilic 31 exhibits self-aggregation in benzene, toluene, and cyclohexane owing to a

• + owing to the intermolecular mix-valence interaction between the TTF•+ and TTF moieties, and the further oxidation forms 313+ [68]. In summary, the oxidation of 28–31 showed multistep processes owing to intra- and/or intermolecular interactions between TTF units. In the case of [18]annulene 31, the first

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• transannular cyclization of 10 using elemental iodine under air [21]. Dehydrobenzo[12]annulene 10 in turn was synthesized via Glaser homocoupling of 1,2-diethynylbenzene [21][22][23]. While in theory this route permitted relatively easy access to diethynyldiones 8, in practice it was fraught with problems: (1

• as the more robust bromines in 11, yet avoid annulene transannular synthesis [24]. Instead, the route we chose involved key precursor 12, which surprisingly is an unknown compound. Starting with commercially available 2,5-dibromo-p-xylene (13) (Scheme 2), iodination using the method reported by

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

• Jakub Saadi,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, 1229–1245, doi:10.3762/bjoc.6.141

• (silica gel, ethyl acetate/hexane 1:9) to furnish 6 (0.126 g, 42%) as colourless crystals (mp 126–127 °C) and 5a (0.069 g, 23%). Methyl (6RS,6aSR,11aRS)-11a-hydroxy-6,6a,7,8,9,10,11,11a,12,13-decahydro-5H-benzo[a]cyclohepta[e][8]annulene-6-carboxylate (6): 1H NMR (CDCl3, 700 MHz): δ = 1.11–1.15, 1.20–1.33

• %) as colourless crystals (mp 74–75 °C). Methyl (4aSR,5RS,11RS,12aRS)-12a-hydroxy-11-methyl-1,2,3,4,4a,5,6,11,12,12a-decahydro-dibenzo[a,e][8]annulene-5-carboxylate (8): 1H NMR (CDCl3, 500 MHz): δ = 1.14–1.18 (m, 2 H, 3-H, 4-H), 1.28 (d, J = 7.0 Hz, 3 H, 11-Me), 1.30–1.34, 1.38–1.46, 1.54–1.58, 1.63

• colourless oil and 10 (0.067 g, 38%) as colourless crystals (mp 130–132 °C). Methyl (6RS,8RS,10RS)-8-hydroxy-8,10-dimethyl-5,6,7,8,9,10-hexahydro-benzo-[8]annulene-6-carboxylate (9): Compound 9 shows temperature-dependent NMR spectra. At rt some signals appear broad; however, for measurements at 55 °C, the

Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

• Venkataramana Rajuri,
• Dariush Ajami,
• Gaston R. Schaller,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2010, 6, No. 30, doi:10.3762/bjoc.6.30

• characterization of new compounds 2–6 were accomplished. As a common synthetic methodology, the Diels–Alder reaction was applied to 9,9′,10,10′-tetradehydrodianthracene (TDDA) (7) to furnish the [12]annulenes 2 and 3 [16]annulene 6 and adduct 5. Keywords: [n]annulenes; Diels–Alder reaction; nanobelts

• aromatic hydrocarbons form 1:1-complexes with silver(I). In all-Z-tribenzo[12]annulene [23], for instance, the Ag+ ion is coordinated by three double bonds in a crown-like geometry. Even although three double bonds with a similar geometry are available in our [12]annulene 2, coordination of the Ag+ ion is

• compounds 5b and 6 in 35% and 4% yield, respectively (Scheme 3) along with dimerization products of diene 10. Compound 6 is formed by a Woodward–Hoffmann symmetry allowed disrotatory electrocyclic ring opening of 5b. Compound 6 is formally a [16]annulene and therefore should be antiaromatic. However, the