78905-08-5Relevant academic research and scientific papers
Iodocyclisation of Electronically Resistant Alkynes: Synthesis of 2-Carboxy (and sulfoxy)-3-iodobenzo[ b ]thiophenes
Chen, Shuqi,Flynn, Bernard L.
, p. 65 - 76 (2020/11/05)
The iodocyclisation of alkynes bearing tethered nucleophiles is a highly effective method for the construction and diversification of heterocycles. A key limitation to this methodology is the 5-endo-dig iodocyclisation of alkynes that have an unfavourable electronic bias for electrophilic cyclisation. These tend to direct electrophilic attack of the iodonium atom to the wrong carbon for cyclisation, thus favouring competing addition reactions. Using our previously determined reaction conditions for the 5-endo-dig iodocyclisations of electronically resistant alkynes, we have achieved efficient synthetic access to 2-carboxy (and sulfoxy)-3-iodobenzo[b]thiophenes. The corresponding benzo[b]furans and indoles were not accessible under these conditions. This difference may arise due to the availability of a radical mechanism in the case of iodobenzo[b]thiophenes. The 2-carboxy functionality of the iodocyclised products can be further employed in iterative alkyne-coupling iodocyclisation reactions, where the carboxy group or an imine (Schiff base) partakes in a second iodocyclisation to generate a lactone or pyridine ring.
Synthesis of (Thio)Furan-Fused Phospholes via Phosphonation Cyclization and a Base-Promoted Phospha-Friedel-Crafts Reaction
Chen, Siyu,Ding, Haixin,Hua, Yuhui,Huang, Haiyang,Li, Chenchen,Liu, Fen,Song, Xian-Rong,Xiao, Qiang,Yuan, Chengxiong
, (2022/02/07)
Herein, we developed a novel strategy for synthesizing ladder (thio)furan-fused phospholes via intermolecular phosphonation cyclization and a base-promoted phospha-Friedel-Crafts reaction under mild conditions. The starting substrates are readily available phosphinic acids and easy-to-handle alkynes. The details of the reaction mechanism were further rationalized using theoretical calculations. This protocol can be widely applied to synthesize furan- and thiofuran-fused phospholes as well as the corresponding large π-extended derivatives, which are of great interest in the domain of organic functional materials.
B(C6F5)3-Catalyzed cyclization of alkynes: direct synthesis of 3-silyl heterocyclic compounds
Li, Mengxing,Wang, Ting,An, Zhenyu,Yan, Rulong
, p. 11953 - 11956 (2020/10/15)
An efficient one-pot strategy for easy access to 3-silyl heterocyclic compounds was developedviaa B(C6F5)3-catalyzed cycloaddition reaction ofo-(1-alkynyl)(thio)anisoles oro-(1-alkynyl)-N-methylaniline. In this reaction, benzenethiophene, benzofuran or indole skeletons could be constructed by an intermolecular cyclization with diphenylsilane. This protocol elicited moderate-to-good yields with metal-free reaction systems.
Polyynes to Polycycles: Domino Reactions Forming Polyfused Chalcogenophenes
Dillon, Annaliese S.,Flynn, Bernard L.
, p. 2987 - 2990 (2020/04/09)
Polyfused chalcogenophenes are prepared in one step through polyelectrophilic cyclization of polyynes using the ambiphilic reagent MeACl (A = S, Se, or Te). Up to four new rings have been generated under mild conditions, including thiophenes, selenophenes, and tellurophenes.
Synthesis of Novel Benzothiophene Derivatives via Cyclization Reactions
Algso, M. A. S.,Hama, A. K.,Kavak, E.,Kivrak, A.
, p. 1272 - 1278 (2020/09/17)
Abstract: The Sonogashira cross coupling reaction of 2-bromo-5-(4-methoxyphenyl)thiophene and 1-ethynyl-2-(methylsulfanyl)benzene gave 2-(4-methoxyphenyl)-5-{[2-(methylsulfanyl)phenyl]ethynyl}thiophene which was subjected to electrophilic cyclization by t
Unexpected formation of 4,7-dihalobenzo[b]thiophenes using Ohira-Bestmann reagent and reactivity of the halogen-substituted benzo[b]thiophenes in Suzuki-Miyaura coupling with phenylboronic acid
Toyota, Kozo,Mutoh, Hirotaka,Kishi, Hiroki,Mikami, Shinichi,Tanaka, Hiroki,Yoshida, Shuhei,Naganuma, Daisuke
, p. 1355 - 1374 (2019/12/23)
Reaction of 2-(1-adamantylsulfanyl)-3,6-dihalobenzaldehydes with Ohira-Bestmann reagent gave 4,7-dihalobenzo[b]thiophenes along with normal alkyne products. Nine types of 4,7-dihalobenzo[b]thiophenes bearing chlorine, bromine, or iodine atoms, were prepared by this method. Regioselectivity in Suzuki-Miyaura cross coupling reactions of the 4,7-dihalobenzo[b]thiophenes with PhB(OH)2 was also studied.
Synthesis of [1]Benzothieno[3,2- b][1]benzothiophene Derivatives via Successive Iodocyclization/Photocyclization of Alkynes
Kitamura, Tsugio,Morita, Kazuhiro,Nakamori, Haruka,Oyamada, Juzo
, p. 4191 - 4199 (2019/03/19)
A new synthetic method for [1]benzothieno[3,2-b][1]benzothiophene derivatives (BTBTs) was developed. The present method consists of iodocyclization of 1,2-bis(2-methylthiophenyl)ethynes and photolysis of 3-iodo-(2-methylthiophenyl)benzo[b]thiophenes. With 1,2-bis(2-methylthiophenyl)ethynes treated with I2/PhI(OAc)2 in CH2Cl2 at room temperature, selective cyclization at sulfur took place to give 3-iodo-(2-methylthiophenyl)benzo[b]thiophenes in good yields. Irradiation of the iodinated benzo[b]thiophenes with a high-pressure Hg lamp (>290 nm) provided BTBTs in good yields. Furthermore, the present method was applied to the synthesis of bis[1]benzothieno[2,3-d;2′,3′-d′]benzo[1,2-b;4,5-b′]dithiophene (BBTBDT).
Toward a Greener Barluenga-Valdés Cross-Coupling: Microwave-Promoted C-C Bond Formation with a Pd/PEG/H2O Recyclable Catalytic System
Lamaa, Diana,Messe, Estelle,Gandon, Vincent,Alami, Mouad,Hamze, Abdallah
supporting information, p. 8708 - 8712 (2019/11/03)
A green Barluenga-Valdés cross-coupling reaction for the synthesis of 1,1-diarylethylenes using palladium catalysis has been developed. The new catalytic system based on Pd/Xphos-SO3Na or Pd/MeDavephos-CF3SO3 in PEG/H2O under microwave irradiation was found to be the best conditions for this transformation. The recyclability of the palladium catalyst system was also studied, and it was found to be active over nine runs without significant loss in its activity.
New strategy for the synthesis of 3-ethynyl-2-(thiophen-2-yl)benzo[b]thiophene derivatives
Algso, Muheb A. S.,Kivrak, Arif
, p. 977 - 985 (2019/04/13)
Pd-catalyzed coupling reactions like the Sonogashira coupling reaction are very useful tools for the formation of new carbon–carbon bonds under mild reaction conditions. Coupling reactions are also used for elaboration of organic compounds in drug and material discovery. Terminal alkynes have a very critical role in Sonogashira coupling reaction. Therefore, design and synthesis of new terminal alkynes are very important for the preparation of organic compounds. In the present study, a novel alkyne 3-ethynyl-2-(thiophen-2-yl)benzo[b]thiophene 13 was synthesized, and it was tested for Sonogashira coupling reaction with different iodoaryl compounds. It was investigated whether our terminal alkyne 13 having a special construction might be a useful precursor for the synthesis of potentially active organic molecules.
Synthesis of 2-substituted benzo[: B] thiophenes via gold(i)-NHC-catalyzed cyclization of 2-alkynyl thioanisoles
Dillon, Christopher C.,Keophimphone, Bagieng,Sanchez, Melissa,Kaur, Parveen,Muchalski, Hubert
supporting information, p. 9279 - 9284 (2019/01/03)
Benzo[b]thiophene heterocycles are important components of many important small molecule pharmaceuticals and drug candidates as well as organic semiconducting materials. Many methods have been developed for the construction of a benzo[b]thiophene core via cyclization reaction of alkynes. Although few catalytic reactions were disclosed, most methods rely on stoichiometric activation of alkynes. Here we report an efficient method for the synthesis of 2-substituted benzo[b]thiophenes from 2-alkynyl thioanisoles catalyzed by a gold(i)-IPr hydroxide that is applicable to a wide range of substrates with diverse electronic and steric properties. Additionally, we demonstrate experimentally that the acid additive and its conjugate base are essential to catalyst turnover.
