77234-10-7Relevant academic research and scientific papers
Highly Efficient Synthesis of 2-Substituted Benzo[ b ]furan Derivatives from the Cross-Coupling Reactions of 2-Halobenzo[ b ]furans with Organoalane Reagents
Wen, Chang,Wu, Chuan,Luo, Ruiqiang,Li, Qinghan,Chen, Feng
, p. 3847 - 3861 (2021/07/02)
A highly efficient and simple route for the synthesis of 2-substituted benzo[ b ]furans has been developed by palladium-catalyzed cross-coupling reaction of 2-halobenzo[ b ]furans with aryl, alkynyl, and alkylaluminum reagents. Various 2-aryl-, 2-alkynyl-, and 2-alkyl-substituted benzo[ b ]furan derivatives can be obtained in 23-97% isolated yields using 2-3 mol% PdCl 2/4-6 mol% XantPhos as the catalyst under mild reaction conditions. The aryls bearing electron-donating or electron-withdrawing groups in 2-halobenzo[ b ]furans gave products in 40-97% isolated yields. In addition, aluminum reagents containing thienyl, furanyl, trimethylsilanyl, and benzyl groups worked efficiently with 2-halobenzo[ b ]furans as well, and three bioactive molecules with 2-substituted benzo[ b ]furan skeleton were synthesized. Furthermore, the broad substrates scope and the typical maintenance of vigorous efficiency on gram scale make this protocol a potentially practical method to synthesize 2-substituted benzo[ b ]furan derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.
Regio- and Stereoselective Synthesis of 1,2-Dihaloalkenes Using In-Situ-Generated ICl, IBr, BrCl, I2, and Br2
Hammond, Gerald B.,Liu, Shiwen,Xu, Bo,Yang, Yi,Yang, Yuhao,Zeng, Xiaojun
supporting information, p. 1018 - 1031 (2020/04/08)
We describe a catalyst-free 1,2-trans-dihalogenation of alkynes with an unprecedented substrate scope and exclusive regio- and stereoselectivity. This versatile dihalogenation system—a combination of NX1S electrophile and alkali metal halide (MX2) in acetic acid—is applicable for diverse categories of alkynes (electron-rich or poor alkynes, internal and terminal alkynes, or heteroatoms such as O-, N-, S-substituted alkynes). The hydrogen bonding donor solvent acetic acid is essential for the in-situ generation of X1X2 electrophile, including ICl, IBr, BrCl, I2, and Br2. Haloalkenes are not only commonly found in biologically active natural products but also have been used extensively in cross-coupling reactions. More specifically, 1,2-dihaloalkenes are especially important synthons because of the presence of two synthetic handles that open a broad avenue to expeditiously generate multisubstituted alkenes. Dihalogenation of alkynes is a straightforward way to prepare 1,2-dihaloalkenes. However, existing alkyne dihalogenation methods either rely on the use of toxic reagents, such as IBr and ICl, lack regio- and stereoselectivity or have limited substrate scope. Thus, the development of a widely applicable and yet efficient alkyne dihalogenation method is still highly desired. Here, we have addressed the aforementioned issues based on an in-situ-generated dihalogenation of reagents, such as ICl and Ibr, by using the readily available N-halosuccinimide (NXS) and alkali metal halides as halogen sources. Our method offers an unprecedented substrate scope, the regio- and stereoselectivity for the synthesis of 1,2-dihaloalkenes. Our simple and mild conditions might find wild applications in the preparation of high-value building blocks for medicines and materials. Dihaloalkenes are important raw materials for pharmaceutical and chemical industries. However, existing preparation methods suffer from a limited substrate scope as well as poor regio- and stereoselectivity. Furthermore, these methods often necessitate highly toxic reagents, such as Cl2, ICl, and BrCl. Our environmentally friendly 1,2-trans-dihalogenation is based on easy-handling halide sources, such as alkali metal halides. What is more, our method offers an unprecedented substrate scope, the regio- and stereoselectivity for the synthesis of 1,2-dihaloalkenes.
Palladium/copper-cocatalyzed decarbonylative alkynylation of acyl fluorides with alkynylsilanes: Synthesis of unsymmetrical diarylethynes
Chen, Qiang,Fu, Liyan,Nishihara, Yasushi
supporting information, p. 7977 - 7980 (2020/09/09)
Palladium/copper-cocatalyzed decarbonylative alkynylation of acyl fluorides with alkynylsilanes is described. This reaction not only effectively inhibits the formation of undesired homocoupled products by avoiding the addition of a base, but also exhibits a wide substrate scope to provide a general access to diverse unsymmetrical diarylethynes.
DBU-Mediated Efficient Synthesis of Diaryl Ethynes and Enynes from 1,1-Dibromoalkenes at Room Temperature
Thummala, Yadagiri,Morri, Ashok K.,Karunakar, Galla V.,Doddi, Venkata Ramana
supporting information, p. 6280 - 6285 (2018/11/23)
The reaction of 1,1-dibromoalkenes and aryl iodides in the presence of DBU and a PdII/CuI catalytic system afforded diaryl alkynes and enynes at ambient temperature. Control experiments demonstrated the essential ligand role of DBU i
Palladium-Catalyzed Decarbonylative Alkynylation of Amides
Liu, Long,Zhou, Dan,Liu, Min,Zhou, Yongbo,Chen, Tieqiao
supporting information, p. 2741 - 2744 (2018/05/22)
A palladium-catalyzed decarbonylative alkynylation of amides via C-N bond activation is developed. Compared with the reported Ni/Cu catalyzed reaction, which only proceeded well with silylacetylenes, this transformation was also applicable to both aromatic and aliphatic terminal alkynes, including those bearing functional groups, and thus provided a general and straightforward access to diverse internal alkynes.
Single electron transfer-induced coupling of alkynylzinc reagents with aryl and alkenyl iodides
Okura, Keisho,Kawashima, Hitomi,Tamakuni, Fumiko,Nishida, Naoya,Shirakawa, Eiji
supporting information, p. 14019 - 14022 (2016/12/09)
Alkynylzinc reagents were found to undergo coupling with aryl and alkenyl iodides to give arylalkynes and alkenylalkynes without the aid of transition metals. The coupling reaction proceeds through a single electron transfer mechanism, where a substoichiometric amount of a phosphine works as an indispensable activator.
A simple and efficient approach to 2-alkynylbenzofurans under mild copper(i)-catalyzed conditions
Liu, Jianming,Zhang, Ningfei,Yue, Yuanyuan,Wang, Dong,Zhang, Yuanli,Zhang, Xin,Zhuo, Kelei
, p. 3865 - 3868 (2013/04/24)
The copper(i)-catalyzed synthetic method for the preparation of 2-alkynylbenzofurans from gem-dihaloolefins has been established using DABCO and TBAF·3H2O as a cocatalyst. This methodology relies on a simple reaction system and inexpensive Cu s
Synthesis of internal alkynes through the Pd-catalyzed coupling of heteroaryl halides with terminal alkynes
Lu, Linhua,Yan, Hong,Sun, Peng,Zhu, Yan,Yang, Hailong,Liu, Defu,Rong, Guangwei,Mao, Jincheng
supporting information, p. 1644 - 1648 (2013/04/10)
Sonogashira-type cross-couplings of functionalized heterocyclic halides with terminal alkynes were performed efficiently at room temperature. The heteroaryl halides were easily prepared from the corresponding heterocyclic compounds. The catalytic system tolerated a very broad scope of substrates; oxazoles, thiazoles, and furans participate in this type of reaction for the first time. This reaction provides an efficient method for the direct functionalization of heterocycles. Sonogashira-type cross-coupling of functionalized heterocyclic halides with terminal alkynes are performed efficiently at room temperature. The catalytic system tolerates a very broad scope of substrates; oxazoles, thiazoles, and furans participate in this type of reaction for the first time. The reaction provides an efficient method for the direct functionalization of heterocycles. Copyright
A highly efficient TBAF-promoted intramolecular cyclization of gem-dibromoolefins for the synthesis of 2-bromobenzofurans(thiophenes)
Chen, Wei,Zhang, Yicheng,Zhang, Lei,Wang, Min,Wang, Lei
supporting information; experimental part, p. 10476 - 10478 (2011/10/31)
A highly efficient tetra-(n-butyl)ammonium fluoride (TBAF)-promoted intramolecular cyclization of gem-dibromoolefins has been developed for the synthesis of 2-bromobenzofused heterocycles. The reaction provides a convenient approach to 2-bromobenzofurans(
Palladium-catalyzed modular assembly of electron-rich alkenes, dienes, trienes, and enynes from (E)-1,2-dichlorovinyl phenyl ether
Geary, Laina M.,Hultin, Philip G.
experimental part, p. 6354 - 6371 (2010/12/19)
We have devised a modular construction of electron-rich alkene derivatives from trichloroethylene (TCE). The three C-l bonds of TCE have sufficiently different reactivities that they can be sequentially and selectively functionalized. Following the substitution of one chlorine by phenol to generate (E)-1,2-dichlorovinyl ether, the C1-Cl group next participates in palladium-catalyzed cross-coupling reactions with a variety of organometallic reagents. Subsequently, the C2-Cl group can engage in cross-couplings, while the C2-H may be deprotonated and quenched with an electrophile. Thus, isomerically pure tri- and tetrasubstituted electron-rich alkenes may be accessed in as few as two steps from simple and inexpensive starting materials. This method is ideally suited for diversity-oriented synthesis of highly conjugated molecules of interest as chromophores or as potential molecular electronics. It also gives access to diverse building blocks for further synthetic elaboration into high-value compounds.
