Copper-Mediated Synthesis of Substituted 2-Aryl-N-benzylbenzimidazoles and 2-Arylbenzoxazoles via C–H Functionalization/C–N/C–O Bond Formation
摘要:
An efficient method for the transformation of N-benzyl bisarylhydrazones and bisaryloxime ethers to functionalized 2-aryl-N-benzylbenzimidazoles and 2-arylbenzoxazoles is described. The protocol involves a copper(II)-mediated cascade C-H functionalization/C-N/C-O bond formation under neutral conditions. Substrates having either electron-donating or -withdrawing substituents undergo the cyclization to afford the target heterocycles at moderate temperature.
Deep eutectic solvent-catalyzed arylation of benzoxazoles with aromatic aldehydes
作者:Phuong Hoang Tran、Anh-Hung Thi Hang
DOI:10.1039/c8ra01094c
日期:——
A novel and efficient methodology for the arylation of benzoxazoles with aromaticaldehydes catalyzed by deep eutectic solvent has been developed. The reaction smoothly proceeded with a wide range of substrates to give the desired products in high yields within short reaction time. Deep eutectic solvents are easily recovered and reused without significant loss of catalytic activity.
p -Toluenesulfonic acid-catalyzed metal-free formal [4 + 1] heteroannulation via N H/O H/S H functionalization: One-pot access to 2-aryl/hetaryl/alkyl benzazole derivatives
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 NH/OH/SH functionalization in one-pot under solventless condition leading to diverse benzazoles without use of any
通过2-氨基(硫代)的级联偶联反应,已公开了一种高产率(80-98%)的简洁,直接的一锅[4 +1]合成策略,用于构建2-取代的苯并唑,如苯并恶唑和苯并噻唑酚与β-氧二硫代酯。目前的方法可以在无溶剂条件下在一锅中实现N H / O H / S H官能化,从而无需使用任何外部金属即可产生多种苯并恶唑。各种各样的2-氨基(硫代)酚和β-氧二硫代酯均具有出色的官能团耐受性,可用于该转化。此外,我们通过证明其与DNA拓扑异构酶II抑制剂的多样化多样化的相容性,抢占了这一新策略的广泛含义。
Palladium-Catalyzed Carbonylative CH Activation of Heteroarenes
Not only carbonylation: The first carbonylative cross‐coupling reactions towards ketones using CH activation have been developed. Various heteroarenes, such as oxazoles, thiazoles, and imidazoles were used as coupling partners in this methodology. DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene, dppp=1,3‐bisdiphenylphosphinopropane, DMF=N,N‐dimethylformamide.
Iron(III) Chloride Mediated
<i>para</i>
‐Selective C‐H Functionalization: Access to C5‐Chloro and C5,C7‐Dichloro/Dianisyl Substituted 2‐Arylbenzoxazoles
作者:Kanchanbala Sahoo、Niranjan Panda
DOI:10.1002/adsc.202101359
日期:2022.3
Iron(III) chloride mediated para-selective C−H chlorination and subsequent annulation of 2-amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles was developed. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole by ferricchloride was explored to achieve the remotely anisylated benzoxazoles.
Synthesis of 2-arylbenzoxazoles via DDQ promoted oxidative cyclization of phenolic Schiff bases—a solution-phase strategy for library synthesis
作者:Junbiao Chang、Kang Zhao、Shifeng Pan
DOI:10.1016/s0040-4039(01)02302-4
日期:2002.2
The Schiff base derived from the condensation of o-aminophenol with benzaldehydes was induced to undergo oxidative cyclization in the presence of DDQ. The resulting 2-arylbenzoxazoles were separated from the reduced DDQ byproduct by treatment of reaction mixture with a strongly basic ion-exchange resin. The applicability of this chemistry to spatially separate library synthesis is demonstrated by the