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Addressing the instability of antiaromatic compounds often involves protection with bulky groups and/or fusion of aromatic rings, thus decreasing paratropicity. We report four naphthothiophene-fuseds-indacene isomers, one of which is more antiaromatic tha

The installation of (benzo)thiophene-containing biaryls via coupling reactions has become a staple in designing photoelectric materials. Undeniably, C-H/C-H cross-coupling reactions between two (hetero)aromatics would be a shortcut toward these structural fragments. While more reliable cross-coupling technologies are well-established to provide C2-arylated (benzo)thiophenes, efficient methods that arylate the C3-position remain underdeveloped. Herein we provide insight into the factors that determine regioselectivity switching for these cross-coupling reactions. X-ray crystallographic analysis gives solid evidence for the key roles of triflate in regioselective dearomatization and acetate in base-assisted anti-β-deprotonated rearomatization. The first isolation and X-ray characterization of a medium-sized dearomatized cyclometalated adduct involving both substrates provide extra insight into aerobic oxidative Ar-H/Ar-H cross-coupling reactions. The mechanistic breakthrough incubates the first example, enabling C-H/C-H-type C3-arylation of benzothiophenes. Finally, this chemistry is used to design blue-emitting thermally activated delayed fluorescence (TADF) materials with a helicene conformation that exhibit a high maximum external quantum efficiency of 25.4% in OLED.

The present invention provides a method for synthesizing phenanthrene and derivatives thereof represented by a formula (III) or (IV). The method is characterized in that a substituted 2-phenylcinnamaldehyde compound represented by a formula (I) or 2-thiophenylcinnamaldehyde represented by a formula (II) is taken as an initial substance, under the effect of a silver catalyst, an oxidant, a basic substance and a solvent, a reaction is carried out at 60 DEG C-100 DEG C for 12-36 hours, the reaction solution is separated and purification is carried out, so that corresponding phenanthrene and derivatives thereof represented by the formula (III) or (IV) are obtained. The synthesis method of the invention has the characteristics of small environmental hazard, mild reaction conditions, simple operation and the like.

The invention provides a method for synthesizing a phenanthrene compound. According to the synthesizing method, a 2-phenyl nitroolefin compound as shown in a formula (I) or a 2-thienyl nitroolefin asshown in the formula (II) is used as an initiator for carrying out a reaction at a temperature of 60-100 DEG C for 4-12 hours under the action of an alkaline substance, a silver catalyst, an oxidizingagent and a solvent, and then the corresponding phenanthrene compound as shown in a formula (III) or a formula (IV) is prepared through separation and purification of a reaction liquid. The synthesizing method disclosed by the invention has the characteristics of small harm to the environment, mild reaction conditions, simple and convenient operation, and the like.

A straightforward and general method for the synthesis of annulated thiophene, dibenzothiophene, and carbazoles analogues has been achieved involving alkylation of 2-bromo-1-(phenylsulfonylmethyl)arene/heteroarene with arylmethyl bromides/heteroarylmethyl bromides using t-BuOK as a base in DMF, followed by Pd(0)-mediated intramolecular Heck coupling in the presence of K2CO3 in DMF at 80-140 °C. The attractive feature of this protocol is that a wide variety of π-conjugated heterocycles could be readily accessed by an appropriate choice of arylmethylsulfones and benzylic bromides.

A highly selective, controllable and synthetically useful base-promoted intramolecular detosylative cyclization of bis-N-tosylhydrazones has been achieved, affording N-containing heterocycles and cyclic olefins under transition-metal-free or gold-catalyzed procedures, respectively. Moreover, an effective and practical metal-free or gold-catalyzed approach to synthesize polycyclic aromatic compounds is also reported. Basic cyclizations: A highly selective, controllable, and synthetically useful base-promoted intramolecular detosylative cyclization of bis-N-tosylhydrazones affords N-containing heterocycles and cyclic olefins under transition-metal-free or gold-catalyzed procedures, respectively. Moreover, an effective and practical metal-free or gold-catalyzed approach to synthesize polycyclic aromatic compounds is also reported.

Ruthenium-catalyzed cycloisomerization of 2-ethynylbiaryls was investigated to identify an optimal ruthenium catalyst system. A combination of [η6-(p-cymene)RuCl2(PR3)] and two equivalents of AgPF6 effectively converted 2-ethynylbiphenyls into phenanthrenes in chlorobenzene at 120 °C over 20 h. Moreover, 2-ethynylheterobiaryls were found to be favorable substrates for this ruthenium catalysis, thus achieving the cycloisomerization of previously unused heterocyclic substrates. Moreover, several control experiments and DFT calculations of model complexes were performed to propose a plausible reaction mechanism.

The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.

Readily available biphenyl derivatives with ortho oxirane moiety react in the presence of cationic chromiun(III) porphyrin catalyst to afford phenanthrenes. The reaction is considered to be triggered by activation of the oxirane moiety through coordination to the Lewis acidic cationic chromium to give aldehyde via 1,2-hydride shift, which reacts with arene through intramolecular electrophilic aromatic substitution and subsequent dehydration. The reaction allows constructing a variety of polycyclic aromatic and heteroaromatic compounds.

Thiophene end-capped aromatic analogues, that is, naphthothiophenes, naphthodithiophenes, pyrenothiophene, and benzotrithiophene, can be prepared from commercially available hydroxyarenes in two steps, including (1) a consecutive acid-mediated nucleophilic aromatic substitution of hydroxyarenes with 2-mercaptoethanol, followed by cyclization to form an arene-fused dihydrothiophene, and (2) oxidation of the dihydrothiophene unit to thiophene.

Ahead of the PAC: Polycyclic aromatic compounds (PACs) can be easily accessed by the combination of Suzuki-Miyaura cross-coupling and a [Rh 2(OAc)4]-catalyzed carbene reaction using easily available bis(N-tosylhydrazone)s as intermediates (see scheme; Ts=4-toluenesulfonyl). Copyright

The direct irradiation of iodoalkenes leads to the formation of carbon-centered radical by homolysis of the C-I bond. The photoreaction is used in cyclizations with formation of six membered rings.

The present invention provides novel naphthothiophene compounds of general formula [1] wherein Ar and R are defined in the present claims, which have a high lowest excited triplet level (T1).

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Isomerization of soluble precursor compounds to produce fused-ring systems is an attractive approach for preparing conjugated polymers and oligomers. Cycloaromatization chemistry has previously been explored in this capacity employing reactions based on the Bergman cyclization. Using ethynyl sulfides with a terminal o-diethynylbenzene unit, an alternative strategy is demonstrated that offers selectivity advantages in the kinetically controlled radical cyclizations. The products are acene-fused thiophenes in which the diethynylsulfide acts as a relay for the diradical produced in a Bergman cyclization.

Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted phenanthrenes on exposure to catalytic amounts of either PtCl2, AuCl, AuCl3, GaCl3 or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-complexation of the alkyne unit followed by interception of the resulting η2-metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-phenanthrenes or into the isomeric 9-halo-phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.

Readily available biphenyl derivatives containing an alkyne unit at one of their ortho positions are converted into substituted phenanthrenes upon exposure to catalytic amounts of either PtCl2, AuCl3, GaCl3, or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-coordination of the alkyne unit followed by interception of the resulting η2-metal complex by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product except C-9. Moreover, the reaction is readily applied to the heterocyclic series as exemplified by the preparation of benzoindoles, naphthothiophenes as well as bridgehead nitrogen hetero- cycles.

Flash vacuum pyrolysis of 3-aroylcinnolines 3 at 900°C and 0.02 Torr yielded phenanthrene and arylacetylene derivatives as the major products beside anthracene and diarylacetylene derivatives as minor products. Also, FVP of 3-(2-thienoyl)-cinnoline gave three isomeric naphthothiophenes, phenyl-2-thienylacetylene and phenylacetylene. On the other hand, 3-(2-furoyl)-cinoline gave dibenzofuran as a major product besides naphtho[1,2-b]furan and phenylacetylene.

The photocyclization, dye-sensitized photooxidation and auto- photooxidation of 3-styrylthiophene have been examined, cis-3-Styrylthiophene undergoes photochemical cis-trans isomerization and cyclization to dihydronaphtho-[1,2-b]thiophene. The quantum efficiency for photocyclization in nonpolar solvents is greater than that in polar solvents. Dye-sensitized photooxidation of 3-styrylthiophene gives benzaldehyde and 3- thiophenecarboxaldehyde. This oxidation proceeds via a superoxide radical anion pathway rather than singlet oxygen pathway. In the presence of oxygen photoirradiation of 3-styrylthiophene solution results in photocyclization, oxidation and dimerization. The mechanism of the latter two reactions was described in terms of formation of a charge transfer complex between oxygen and the substrate. (C) 2000 Elsevier Science Ltd.

The FVP method of ethynyl and chlorovinyl materials is applied to the ready formation of sulfur-containing fused heteroaromatic systems. The pyrolysis of the chlorovinyl materials is assumed to involve a mechanism different from that of the ethynyl materials.

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Naphthylthiyl radicals 1-C10H7S, generated during the thermolysis of 1-C10H7SH, (1-C10H7)2S2, and 1-C10H7SCH2CH=CH2 and also from the 1-C10H7X-H2S system (X = Cl, Br), react with acetylene at 410-700 deg C, forming naphthothiophene and naphthothiopyran.Under certain conditions the yield of each of these difficulty obtainable heterocycles under certain conditions amounts to 47 and 60percent respectively.

2,3-Dihydro-2,3-bis-(methylene)thiophene and its benzo derivate, generated flash-pyrolytically, polymerise or are trapped with HCl and PhSH but only the latter gives Diels-Alder adducts; electrocyclisation of the 3-phenylmethylene derivate is accompained by skeletal rearrangement to give naphthothiophene.

Alkanethiols react effectively with chlorobenzene, its derivatives, 1-chloronaphthalene, and 2-chlorothiophene at 600-660 deg C with the preferential formation of the corresponding aromatic or heteroatomic thiols.Ethanethiol is most reactive.When it is used instead of hydrogen sulfide in reactions with chlorobenzene or its 4-substituted derivatives, the yield of the aromatic thiols, from which the phenylthiyl radicals are generated with greater difficulty, increases more sharply than the yield of the thiophenols, which generate the more stable 4-XC6H4S radicals.The side products of the reactions are the corresponding diaryl sulfides, thiophene, benzothiophene, and toluene.

The synthesis of naphthothiophene and all of the eight monomethylnaphthothiophene isomers is described.

A new method for the preparation of naphtho- and naphthothiophene structures by arylation of acrylic acid with α- and β-iodonaphthalene and subsequent oxidation of the resulting trans-naphthylacrylic acids with thionyl chloride in the presence of triethylbenzylammonium chloride is proposed.

The products from the reaction of chlorobenzene with dialkyl disulfides in the gas phase at 550-650 deg C are benzene, thiophenol, diphenyl sulfide, and also toluene, thiophene, and benzothiophene.Diethyl disulfide is most reactive.Its copyrolysis with chlorobenzene is distinguished by high selectivity for the formation of thiophenol, the yield of which amounts to 60percent.In the reaction of substituted chlorobenzenes and also 2-chlorothiophene and 1-chloronaphthalene with diethyl disulfide the corresponding thiols were obtained with high yields.Two paths for the formation of thiophene during the pyrolysis of dialkyl disulfide were established, i.e., from vinyl hydrosulfide and S-butyl radical.The last reaction is realized at a high rate.