- Synthesis of Benzo[b]thiophenes through Rhodium-Catalyzed Three-Component Reaction using Elemental Sulfur
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A benzo[b]thiophene synthesis by Rh-catalyzed three-component coupling reaction of arylboronic acids, alkynes, and elemental sulfur (S8) is developed. A notable feature of this protocol is that the thienannulation (thiophene annulation) proceeds with high regioselectivity via the sequential alkyne insertion, C?H activation, and then sulfur atom transfer to the metallacycle intermediate. In a similar manner, dibenzothiophenes can be synthesized from the parent biarylboronic acids and S8. (Figure presented.).
- Moon, Sanghun,Kato, Moena,Nishii, Yuji,Miura, Masahiro
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supporting information
p. 1669 - 1673
(2020/03/23)
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- A Pd-catalyzed optional approach for the synthesis of dibenzothiophenes
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A direct and practical approach for the construction of DBTs was developed via a Pd-catalyzed tandem reaction, in which commercially available o-bromo-iodobenzenes combined with benzene thiols or iodobenzenes combined with o-bromo-benzene thiols were applied. These two approaches will provide an alternative for the synthesis of DBT derivatives.
- Song, Juan,Wu, Hao,Sun, Wei,Wang, Songjiang,Sun, Haisen,Xiao, Kang,Qian, Yan,Liu, Chao
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supporting information
p. 2083 - 2087
(2018/03/26)
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- Palladium catalysis based one-pot synthesis method for DBTs (dibenzothiophenes)
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The invention discloses a palladium catalysis based one-pot synthesis method for DBTs (dibenzothiophenes). An inorganic base is added to an N,N-dimethylacetamide solution, with a palladium catalyst/ligand as a catalysis system, o-bromoiodobenzene derivatives or iodobenzene derivatives and thiophenol derivatives taken as raw materials are subjected to a reaction in nitrogen atmosphere, and DBTs areobtained through separation. The simple, economical and easily available raw materials are taken as substrates, all-position-substituted DBTs are synthesized on the basis of palladium catalyzed cascade reaction, and DBTs have great application prospect in medical synthesis intermediates and organic optoelectronic material science.
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Paragraph 0033-0038
(2020/05/12)
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- Ultrasound assisted Bradsher reaction in aqueous and non-aqueous media: First use of ultrasounds in electrophilic aromatic cyclisation leading to polyacenes
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The present work describes the first use of ultrasounds in the Bradsher cyclisation of activated and non-activated ortho-formyl diarylmethanes. This reaction is also the first example of electrophilic, aromatic cyclisation assisted by ultrasounds which leads to pure polycyclic, fused aromatic hydrocarbons containing 3 and 4 fused rings in excellent yields. The reaction proceeds not only in aqueous but also in non-aqueous media at milder conditions (room temperature) and in much shorter reaction times than in conventional protocols.
- Kowalska, Emilia,Ba?czewski, Piotr
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p. 743 - 753
(2016/07/25)
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- Synthesis of annulated arenes and heteroarenes by hydriodic acid and red phosphorus mediated reductive cyclization of 2-(Hetero)aroylbenzoic acids or 3-(Hetero)arylphthalides
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Annulated arenes and hetarenes were prepared in good to very good yields by hydriodic acid/red phosphorus mediated reductive cyclization of 3-(hetero)aryl phthalides. The reductive cyclization also proceeded successfully with 2-aroylbenzoic acids and 2-aroylnaphthoic acids.
- Rafiq, Settu Muhamad,Mohanakrishnan, Arasambattu K.
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supporting information
p. 362 - 370
(2017/02/10)
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- Palladium(ii)-catalyzed synthesis of dibenzothiophene derivatives via the cleavage of carbon-sulfur and carbon-hydrogen bonds
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A new process has been developed for the palladium(ii)-catalyzed synthesis of dibenzothiophene derivatives via the cleavage of C-H and C-S bonds. In contrast to the existing methods for the synthesis of this scaffold by C-H functionalization, this new catalytic C-H/C-S coupling method does not require the presence of an external stoichiometric oxidant or reactive functionalities such as C-X or S-H, allowing its application to the synthesis of elaborate π-systems. Notably, the product-forming step of this reaction lies in an oxidative addition step rather than a reductive elimination step, making this reaction mechanistically uncommon.
- Tobisu, Mamoru,Masuya, Yoshihiro,Baba, Katsuaki,Chatani, Naoto
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p. 2587 - 2591
(2016/04/05)
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- Synthesis of Annulated Anthracenes, Carbazoles, and Thiophenes Involving Bradsher-Type Cyclodehydration or Cyclization-Reductive-Dehydration Reactions
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A conventional BF3·OEt2-mediated Bradsher-type cyclodehydration of 2-arylmethyl benzaldehydes in CH2Cl2 at room temperature gave polycyclic aromatic and heteroaromatic compounds. Alternatively, these compounds could be synthesized in better yields from 2-arylmethylbenzoic acids by triflic-acid-mediated cyclization followed by reductive dehydration.
- Rafiq, Settu Muhamad,Sivasakthikumaran, Ramakrishnan,Karunakaran, Jayachandran,Mohanakrishnan, Arasambattu K.
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p. 5099 - 5114
(2015/08/18)
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- Lewis acid/Broensted acid mediated benz-annulation of thiophenes and electron-rich arenes
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A facile preparation of benz-annulated heterocycles were achieved at rt involving a Lewis acid/Broensted acid mediated annulation of heterocycles using 2,5-dimethoxytetrahydrofuran as a four-carbon synthon. The benz-/naphth-annulation was found to be successful with electron-rich arenes as well.
- Rafiq, Settu Muhamad,Sivasakthikumaran, Ramakrishnan,Mohanakrishnan, Arasambattu K.
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supporting information
p. 2720 - 2723
(2014/06/09)
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- Synthesis of dibenzothiophenes by pd-catalyzed dual C-H activation from diaryl sulfides
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Palladium-catalyzed dual C-H functionalization of diaryl sulfides to form dibenzothiophenes (DBTs) by oxidative dehydrogenative cyclization is reported. This protocol afforded various DBTs in moderate to good yields with tolerance of a wide variety of substrates. Benzo[1,2-b:4,5-b]bis[b]benzothiophene was successfully synthesized by this method, which was used as an organic semiconductor for field-effect transistors.
- Che, Rui,Wu, Zhiqing,Li, Zhengkai,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 7258 - 7261
(2014/06/23)
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- Lewis acid mediated one-pot synthesis of aryl/heteroaryl-fused carbazoles involving a cascade Friedel-Crafts alkylation/electrocyclization/aromatization reaction sequence
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A Lewis-acid-mediated domino reaction of 2/3-(bromomethyl)indoles with arenes/heteroarenes led to the formation of the corresponding annulated carbazoles. This three-step one-pot transformation proceeds by sequential Lewis acid catalysed Friedel-Crafts alkylation, electrocyclization and aromatization reactions. The strategy is highly efficient for the assembly of complex aryl/heteroaryl-fused carbazoles.
- Sureshbabu, Radhakrishnan,Saravanan, Velu,Dhayalan, Vasudevan,Mohanakrishnan, Arasambattu K.
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p. 922 - 935
(2011/04/22)
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- A versatile synthesis of annulated carbazole analogs involving a domino reaction of bromomethylindoles with arenes/heteroarenes
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A ZnBr2-mediated arylation of aryl/heteroaryl methyl bromides with arenes at 80°C led to the formation of arylated products, which underwent subsequent 1,5-sigmatropic rearrangement followed by electrocyclization and aromatiza tion with loss of a diethylmalonate unit to afford the corresponding annulated products.
- Dhayalan, Vasudevan,Clement, J. Arul,Jagan, Radhakrishnan,Mohanakrishnan, Arasambattu K.
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experimental part
p. 531 - 546
(2009/09/06)
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- Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
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A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
- Fullana,Font,Conesa,Blasco
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p. 2092 - 2099
(2007/10/03)
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- The Desulfurization of Polynuclear Aromatic Sulfur Compounds with a Raney Nickel
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The mechanism of the desufulization of the polynuclear thiophene compounds with a Raney nickel was studied in ethanol at atmospheric pressure and from 0 to 73.3 degC.The desulfurization rate was initially fast but reached zero in about 30 minutes.The major products were biphenyl in the desulfurization of dibenzothiophene (1), 1-phenylnaphthalene in the desulfurization of benzonaphthothiophene (2), and 2-phenylnaphthalene in the reaction of benzonaphthothiophene (3) and benzonaphthothiophene (4).The desulfurization extent for the four compounds decreased in this sequence: 3>1>2>4.The extent of the desulfurization of the polynuclear thiophene compound was not related to the reaction indices, Fr(E), Fr(N), and Fr(R), of the sulfur atom of the compounds, which were calculated by using a simple Hueckel theory; rather, it was related to both the free valence and the ?-electron density.Therefore, the polynuclear thiophene compounds were considered to adsorb on a Raney nickel through the free-electron pair of the sulfur atom; consequently, the adsorption led to the C-S bond scission.
- Nagai, Masatoshi,Urimoto, Hideo,Uetake, Kazuya,Sakikawa, Noriyuki,Gonzalez, Richard D.
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p. 557 - 562
(2007/10/02)
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- The Insertion and Extrusion of Heterosulfur Bridges. XV. S-Bridging of 2,2'-Binaphthyl and 1-(2-Naphthyl)cyclohexene. Studies on Hydrodehalogenation During the Reaction
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Regioselectivity occurs in the sulfur-bridging reactions of 2,2'-binaphthyl (1) and 1-(2-naphthyl)cyclohexene (7) by means of hydrogen sulfide and a chromia-alumina-magnesia catalyst (designated I) in a flow apparatus at 550 deg C.Thus, 1 gives a higher yield (6.1percent of dinaphthothiophene from 1,1'-bridging than of dinaphthothiophene (3.4percent) from 1,3'-bridging.No product expected from 3,3'-bridging was identified.Substrate 7 undergoes both dehydrogenation and bridging to yield 2-phenylnaphthalene (8percent), benzonaphthothiophene (9percent) from alpha briding, and benzonaphthothiophene (3percent) from beta bridging into the naphthalene ring.Exploratory studies showed that either sulfided catalyst I or a sulfided molybdenum(VI) oxide-alumina-cobalt(II) oxide catalyst (II) effects hydrodehalogenation of various monohalo- and polyhaloarenes (where halo, X, is chloro or bromo) at 450-550 deg C.In the biphenyl, phenanthrene, naphthalene, and pyrene systems, halogen was lost either under sulfur-bridging conditions or under hydrogenolysis conditions, i.e. with methanol as a reactant.For every substrate the parent arene was isolated or identified as a reaction product.In selected experiments, acid HX was also identified in the effluent.Use of hydrogen sulfide as a reactant led to formation of dibenzothiophene and phenanthrothiophene as main products in the biphenyl and phenanthrene systems, respectively; while use of methanol as a reactant gave small amounts of methyl bromide (for X = Br) and methylarenes.
- Klemm, L. H.,Stevens, Michael P.,Tran, Long K.,Sheley, John
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p. 1111 - 1116
(2007/10/02)
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- Thiophene analogues of carcinogenic polycyclic hydrocarbons. Elbs pyrolysis of various aroylmethylbenzo[b]thiophenes
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The synthesis of two benzonaphthothiophenes and of four benzophenanthrothiophenes through Elbs cyclodehydration of ortho-methylated aroylbenzo[b]thiophenes is described. The occurrence of a rearrangement of the thiophene ring in the course of the cyclization is discussed as well as the influence of the temperature on a concurrent cyclodehydration process. Several of these poly-condensed thiophenes were found to be carcinogenic in mice.
- Croisy,Mispelter,Lhoste,et al.
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p. 353 - 359
(2007/10/02)
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- Synthesis of Anthrathiophenes and Benzonaphthothiophenes
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All isomers of the parent anthrathiophenes and benzonaphthothiophenes, namely anthrathiophene, anthrathiophene, anthrathiophene, benzonaphthothiophene, benzonaphthothiophene and benzonaphthothiophene were synthesized using a new procedure.
- Tominaga, Yoshinori,Lee, Milton L.,Castle, Raymond N.
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p. 967 - 972
(2007/10/02)
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