17064-45-8Relevant academic research and scientific papers
Delivering 2-Aryl Benzoxazoles through Metal-Free and Redox-Neutral De-CF3Process
Qiao, Xinxin,Zhao, Yong-De,Rao, Mingru,Bu, Zhan-Wei,Zhang, Guangwu,Xiong, Heng-Ying
, p. 13548 - 13558 (2021/10/01)
An unexpected cleavage of the Csp3-CF3 bond of CF3-hydrobenzoxazoles has been disclosed, affording a range of 2-aryl benzoxazoles under metal-free and redox-neutral conditions. This transformation has demonstrated broad substrate scope and good compatibility of functional groups. 2-Aryl benzothiazole and 2-aryl benzoimidazole could be smoothly assembled in the same manner. On the basis of preliminary mechanistic studies, base initiated and aromatization driven β-carbon elimination was considered to be the key step for the formation of 2. This reaction offers an alternative, facile, and sustainable route to access important 2-aryl benzoxazole motifs.
Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
, p. 10690 - 10699 (2021/04/09)
Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
Visible Light-Induced Copper-Catalyzed C—H Arylation of Benzoxazoles?
Ma, Xiaodong,Zhang, Guozhu
supporting information, p. 1299 - 1303 (2020/08/05)
A general method for visible light-induced copper-catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron-poor heterocycles such as thiophene possessing one electron-withdrawing group can also be arylated.
Facile access to libraries of diversely substituted 2-aryl-benzoxazoles/benzothiazoles from readily accessible aldimines via cyclization/cross coupling in imidazolium-ILs with Pd(OAc)2 or NiCl2 (dppp) as catalyst
Malunavar, Shruti S.,Sutar, Suraj M.,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
supporting information, (2019/12/24)
A two-step protocol involving Pd-catalyzed cyclization of readily accessible p-bromophenyl-aldimines to 2-bromophenyl-benzoxazole/benzothiazole in [BMIM][PF6] or [BMIM][BF4] as solvent, followed by the Suzuki, Heck, and Sonogashira cross-coupling reactions catalyzed by Pd or Ni is described that generates libraries of diversely substituted 2-aryl-/heteroaryl-benzoxazoles/benzothiazoles in respectable isolated yields under mild reaction conditions. The feasibility to perform the two-steps in sequence in one-pot starting from the aldimines is also demonstrated and the potential for recycling/reuse of the IL solvent is also shown.
Ni-Catalyzed C?F Bond Functionalization of Unactivated Aryl Fluorides and Corresponding Coupling with Oxazoles
Yin, Youzhi,Yue, Xiaoyu,Zhong, Qi,Jiang, Hanmin,Bai, Ruopeng,Lan, Yu,Zhang, Hua
supporting information, p. 1639 - 1643 (2018/03/21)
A Ni-catalyzed C?F bond functionalization of unactivated aryl fluorides with oxazoles as coupling partners was developed. Various arylated oxazoles could be obtained in moderate to good yields in the presence of Ni(cod)2/IMes catalytic system.
p-Toluenesulfonic acid-catalyzed metal-free formal [4?+?1] heteroannulation via N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization: One-pot access to 2-aryl/hetaryl/alkyl benzazole derivatives
Srivastava, Abhijeet,Shukla, Gaurav,Singh, Maya Shankar
, p. 879 - 887 (2017/01/25)
A concise and direct one-pot [4?+?1] synthetic strategy for the construction of 2-substituted benzazoles such as benzoxazoles and benzothiazoles has been disclosed in high yields (80–98%) by cascade coupling reaction of 2-amino(thio)phenols with β-oxodithioesters. The current approach enables N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization in one-pot under solventless condition leading to diverse benzazoles without use of any external metal. A wide range of 2-amino(thio)phenols and β-oxodithioesters are compatible toward this transformation with excellent functional group tolerance. Furthermore, we preempt the wider implications of this novel strategy by demonstrating its compatibility toward versatile diversification of DNA Topoisomerase-II inhibitors.
S8-Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles
Gan, Haifeng,Miao, Dazhuang,Pan, Qiang,Hu, Renhe,Li, Xiaotong,Han, Shiqing
supporting information, p. 1770 - 1774 (2016/07/07)
A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product.
High-Throughput Screening Protocol for the Coupling Reactions of Aryl Halides Using a Colorimetric Chemosensor for Halide Ions
Eom, Min Sik,Noh, Jieun,Kim, Han-Sung,Yoo, Soyeon,Han, Min Su,Lee, Sunwoo
supporting information, p. 1720 - 1723 (2016/05/19)
Mercury complex of 4-(2-pyridylazo)resorcinol (PAR-2Hg2+), a halide-ion chemosensor, was prepared and its efficiency as a tool for high-throughput screening (HTS) of transition-metal-catalyzed coupling reactions was investigated. It showed a high selectivity for halide ions. When the PAR-2Hg2+ complex was used in the Suzuki coupling reaction and C-H activated coupling reaction with aryl bromides, the quantitative and qualitative conversions of aryl halides were obtained from the reaction mixture color change.
Palladium-catalyzed coupling of azoles or thiazoles with aryl thioethers via C-H/C-S activation
Zhu, Feng,Wang, Zhong-Xia
supporting information, p. 1601 - 1604 (2015/03/30)
Palladium-catalyzed cross-coupling via the Csp2-S bond activation of aryl thioethers and the C-H bond activation of azoles or thiazoles was carried out. Electron-deficient and -rich aryl methyl thioethers and diaryl thioethers can be employed as the coupling partners and the reaction tolerates a range of functional groups including MeO, CF3, CN, PhCO, CONEt2, and Py groups.
An iron and copper system catalyzed C-H arylation of azoles with arylboronic acids
Hu, Wei-Ye,Wang, Pei-Pei,Zhang, Song-Lin
supporting information, p. 42 - 48 (2015/02/02)
An efficient, environmentally friendly, and economical new method for arylation reactions of azoles with arylboronic acids via copper-iron-catalyzed C-H and C-B bond activation has been developed. The protocol tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and trifluoromethyl groups.
