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1.
Robert W. Miller Alexandra K. Duncan Dr. Severin T. Schneebeli Dr. Danielle L. Gray Prof. Adam C. Whalley 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3705-3711
In 1976, the first attempted synthesis of the saddle‐shaped molecule [8]circulene was reported. The next 37 years produced no advancement towards the construction of this complicated molecule. But remarkably, over the last six months, a flurry of progress has been made with two groups reporting independent and strikingly different strategies for the synthesis of [8]circulene derivatives. Herein, we present a third synthetic method, in which we target tetrabenzo[8]circulene. Our approach employs a Diels–Alder reaction and a palladium‐catalyzed arylation reaction as the key steps. Despite calculations describing the instability of [8]circulene, coupled with the reported instability of synthesized derivatives of the parent molecule, the addition of four fused benzenoid rings around the periphery of the molecule provides a highly stable structure. This increased stability over the parent [8]circulene was predicted by using Clar’s theory of aromatic sextets and is a result of the compound becoming fully benzenoid upon incorporation of these additional rings. The synthesized compound exhibits remarkable stability under ambient conditions—even at elevated temperatures—with no signs of decomposition over several months. The solid‐state structure of this compound is significantly twisted compared to the calculated structure primarily as a result of crystal‐packing forces in the solid state. Despite this contortion from the lowest‐energy structure, a range of structural data is presented confirming the presence of localized aromaticity in this large polycyclic aromatic hydrocarbon. 相似文献
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Per‐Substituted [8]Circulene and Its Non‐Planar Fragments: Synthesis,Structural Analysis,and Properties 下载免费PDF全文
Chieh‐Ning Feng Wen‐Ching Hsu Jen‐Yi Li Prof. Ming‐Yu Kuo Prof. Yao‐Ting Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9198-9208
The syntheses, structures, and physical properties of a full series of benzannulated tetraphenylenes are reported. The palladium‐catalyzed annulation of tetraiodo‐substituted 2,3,6,7,10,11,14,15‐octamethyltetraphenylene with insufficient di(4‐anisyl)ethyne yielded a mixture of per‐substituted [8]circulene and its non‐planar fragments, including mono‐, para‐di‐, ortho‐di‐, and triannulated products. Their structures were unambiguously verified by X‐ray crystallography. Successive benzannulations significantly affect the molecular geometries, dynamic behaviors, and physical properties of the compounds. In this series of compounds, [8]circulene is the most strained one, as reflected by the significant deplanarization of the phenanthrene moieties (ca. 63° in the bay region) and the fact that it has the highest strain energy (120.6 kcal mol?1). The dynamic behaviors of these compounds were examined both experimentally and theoretically. The ring flipping of per‐substituted [8]circulene is confirmed to proceed through pseudorotation with a barrier of around 21 kcal mol?1, whereas its non‐planar fragments require much more energy for the ring inversion. The photophysical and electrochemical properties of the investigated compounds depend strongly on the extent of efficient π conjugation. The successive benzannulations red‐shift both the absorption and the emission bands, and reduce the first oxidation potential. 相似文献
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Herbert Meier 《中国化学快报》2012,23(5):509-511
The first synthesis of pillar[7]arene is reported with two methods.Method A:the FeCl3-catalyzed condensation reaction of 1,4- dimethoxybenzene(1) with paraformaldehyde in CHCl3 gave dimethoxypillar[7]arene(3).Method B:the p-toluenesulfonic acid catalyzed condensation reaction of 2,5-bis(benzyloxymethyl)-1,4-dimethoxybenzene(2) in CH2Cl2 gave compound 3.Demethylation of 3 with BBr3 gave pillar[7]arene(4).The pillar[7]arene might be a perspective macrocyclic host in host-guest chemistry. 相似文献
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Tadanobu Sawada Hiroyuki Ishii Yoshitomo Aoyama Toyotoshi Ueda Junji Aoki Minoru Takekawa 《合成通讯》2013,43(6):784-793
7H-Naphtho[1,8-gh]quinolin-7-one was prepared by the glycerol condensation of 3-aminophenalenone in good yields. This method provides a new and convenient synthesis of the compound. NMR spectra of its related compounds were measured, and the rapid interchange between two equivalent α-enone structures was found, which is well known as the phenomenon for the formation of carboxylic acid dimer or hydrogen difluoride ion. 相似文献
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S. Taghvaei-Ganjali 《Supramolecular chemistry》2013,25(5):527-530
A new Dimeric calixarene from the head to head linkage of two calix[4]arene units fixed in the cone conformation was synthesized via Sonogashira cross-coupling reaction. The structure of 10 was confirmed by NMR, MS and IR-spectroscopy. 相似文献
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A Quintuple [6]Helicene with a Corannulene Core as a C5‐Symmetric Propeller‐Shaped π‐System 下载免费PDF全文
Kenta Kato Prof. Dr. Yasutomo Segawa Prof. Dr. Lawrence T. Scott Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2018,57(5):1337-1341
The synthesis and structural analysis of a quintuple [6]helicene with a corannulene core is reported. The compound was synthesized from corannulene in three steps including a five‐fold intramolecular direct arylation. X‐ray crystallographic analysis revealed a C5‐symmetric propeller‐shaped structure and one‐dimensional alignment in the solid state. The enantiomers of the quintuple [6]helicene were successfully separated by HPLC, and the chirality of the two fractions was identified by CD spectroscopy. A kinetic study yielded a racemization barrier of 34.2 kcal mol?1, which is slightly lower than that of pristine [6]helicene. DFT calculations indicate a rapid bowl‐to‐bowl inversion of the corannulene moiety and a step‐by‐step chiral inversion pathway for the five [6]helicene moieties. 相似文献
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Dr. David Roy Hiroyuki Maekawa Dr. Masahito Murai Prof. Dr. Kazuhiko Takai 《化学:亚洲杂志》2015,10(11):2518-2524
[5]Phenacene with trimethylsilyl groups at the axis positions was synthesized by the ruthenium‐catalyzed direct C?H arylation of a 1‐formyl‐7‐phenanthrene‐derived aldimine, followed by sequential Wittig olefination and bismuth‐catalyzed cyclization of the resulting vinyl ethers. By using the same synthetic building blocks and sequential Wittig olefination and photocyclization, the number of fused benzene rings was readily increased to seven to afford 3,12‐disilyl[7]phenacene. The introduction of silyl groups endowed the [n]phenacene frameworks with good solubility, as well as enabling further functionalization. The electronic structure of these new [n]phenacenes was determined by photophysical measurements and by density functional theory calculations, which clearly implied effective conjugation throughout the entire π framework. 相似文献
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Bodil Lousen Dr. Stephan K. Pedersen Pernille Bols Kasper H. Hansen Michelle R. Pedersen Prof. Ole Hammerich Dr. Sergey Bondarchuk Prof. Boris Minaev Dr. Glib V. Baryshnikov Prof. Hans Ågren Prof. Michael Pittelkow 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):4935-4940
This work describes a synthetic approach where a non-planar aromatic heterocyclic [7]helicene is compressed to yield a hetero[8]circulene containing an inner antiaromatic cyclooctatetraene (COT) core. This [8]circulene consists of four benzene rings and four heterocyclic rings, and it is the first heterocyclic [8]circulene containing three different heteroatoms. The synthetic pathway proceeds via a the flattened dehydro-hetero[7]helicene, which is partially a helicene and partially a circulene: it is non-planar and helically chiral as helicenes, and contains a COT motif like [8]circulenes. The antiaromaticity of the COT core is confirmed by nucleus independent chemical shift (NICS) calculations. The planarization from a helically π-conjugated [7]helicene to a fully planar heterocyclic [8]circulene significantly alters the spectroscopic properties of the molecules. Post-functionalization of the [7]helicenes and the [8]circulenes by oxygenation of the thiophene rings to the corresponding thiophene-sulfones allows an almost complete fluorescence emission coverage of the visible region of the optical spectrum (400–700 nm). 相似文献
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An efficient synthesis of a 1,4-disubstituted 7-oxabicyclo[2.2.1]heptane intermediate and its subsequent conversion to a potential PAF antagonist is described. 相似文献
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Dr. Chihiro Maeda Shuichi Nomoto Koki Akiyama Dr. Takayuki Tanaka Prof. Tadashi Ema 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(63):15699-15705
Carbazole-based aza[7]helicenes and hetero[9]helicenes were successfully obtained via the intramolecular Scholl reaction of 3,6-bis(biphenyl-2-yl)carbazole congeners, while the reaction of 3,6-bis(naphthylphenyl)-appended carbazole gave a triple helicene via an unexpected simultaneous double aryl rearrangement. DFT calculations suggested that the rearrangement proceeded via an arenium cation intermediate. In addition, the reaction of methoxy-appended substrate gave an azahepta[8]circulene via the concurrent C−C bond formation. These helical dyes showed circularly polarized luminescence. The azahepta[8]circulene was further transformed into deeply saddle-distorted dibenzodiaza[8]circulenes as the first example of its solution-based synthesis and unambiguous structural determination. 相似文献
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Sebastian Hahn Philipp Biegger Markus Bender Dr. Frank Rominger Prof. Uwe H. F. Bunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):869-873
Thermal condensation of 2,3‐diamino‐1,4‐(bistriisopropylsilylethynyl)benzene, ‐naphthalene,‐anthracene, and ‐benzothiadiazole substrates with 1,2‐naphthalenedione forms bent benzophenazine‐type heteroarenes in a one‐step reaction in good to excellent yields. The targets are investigated by UV/Vis spectroscopy, cyclic voltammetry, and single‐crystal X‐ray crystallography. The packing of the targets in the solid state follows either a herringbone or a brick wall motif. In the case of 8,13‐bis(triisopropylsilylethynyl)dibenzo[a,i]phenazine, polymorphs with either packing result. 相似文献
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Russian Journal of Organic Chemistry - The reaction of methyl 2-azido-5-bromobenzoate with ethyl 4-(ethylsulfanyl)-3-oxobutanoate was used to synthesize ethyl... 相似文献
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Abdelwaheb Hamdi Rym Abidi Zouhair Asfari Jacques Vicens 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(1-2):97-105
The synthesis of four new tetraamido-type p-tert-butylcalix[4]arenes presenting two proximal binding subunits is reported. Complexation of alkalimetals and zinc picrates with these ligands have been carried out and monitored by 1H-NMR inCDCl3. It is shown that hard cations are included in the tetraamido cavity while thezinc cation is chelated to the pyridine rings of one of the ligands. The formation of a 1:1:1heterobinuclear complex is also described 相似文献
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Raghuram Reddy Kothur Flavia Fucassi Gennaro Dichello Ludovic Doudet Wafa Abdalaziz Bhavik Anil Patel 《Supramolecular chemistry》2016,28(5-6):436-443
AbstractA novel copillar[4+1]arene incorporating alkylthiol substituents was synthesised in three steps and structurally characterised as the first example of a pillar[n]arene to incorporate two terminal thiols on the same aromatic ring. The macrocycle was attached to gold electrodes through a standard dipping technique. Cyclic voltammetry demonstrated selectivity for Li+ over other alkali metal cations. The copillar[4+1]arene was also used as a capping agent in the preparation of 3 nm gold nanoparticles. 相似文献
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Alexandre Mathieu Zouhair Asfari Jacques Vicens Pierre Thuéry Martine Nierlich 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):133-135
The reaction of p-tert-butyl calix[4]arene 1 with,'-dibromo-o-xylene in basic conditions leads totwo new compounds. One of them is a bis-calix[4]arene, whose crystal structure has been determined. 相似文献