Base-mediated intramolecular cyclization of (2-propargyl ether) arylimines: an approach to 3-amino-benzofurans
摘要:
We present here a practical synthesis of functional 3-amino-benzofurans through base-promoted intramolecular cyclization of (2-propargyl ether) arylimines. A systematic study of the cyclization system revealed that the presence and the amount of base played an essential role in this reaction. The results showed that the cyclization proceeded cleanly and smoothly under mild reaction conditions, employing potassium tert-butoxide as base, THF as solvent, at room temperature in a short reaction time (1 h). The generality of this reaction has been established with (2-propargyl ether) arylimines having both electron-withdrawing and electron-donating groups. (C) 2014 Elsevier Ltd. All rights reserved.
Borylative Cyclization of 1,6-Allenynes Driven by BCl<sub>3</sub>
作者:Chun-Hua Yang、Xiangkun Sun、Congcong Niu、Zhiwei Zhang、Mingzhu Liu、Fangjie Zheng、Ling Jiang、Xiangtao Kong、Zhantao Yang
DOI:10.1021/acs.orglett.1c03062
日期:2021.10.15
A metal-free intramolecular borylative cyclization of 1,6-allenynes driven by BCl3 was developed. This method provides a general and practical strategy to construct valuable pyrrolidines containing all-carbon quaternary centers or 3,5-dihydroazepine derivatives depending on the substituents of the allene, with conjugative and sterically hindered phenyl groups favoring the latter.
enantioselective synthesis of highly functionalized chiral cyclopent-2-enones by the reaction of alkynyl malonate esters with arylboronic acids is described. These desymmetrizing arylative cyclizations are catalyzed by a chiral phosphinooxazoline/nickel complex, and cyclization is enabled by the reversible E/Z isomerization of alkenylnickel species. The general methodology is also applicable to the synthesis of
Synthesis of Carbolines via Palladium/Carboxylic Acid Joint Catalysis
作者:Gianpiero Cera、Matteo Lanzi、Davide Balestri、Nicola Della Ca’、Raimondo Maggi、Franca Bigi、Max Malacria、Giovanni Maestri
DOI:10.1021/acs.orglett.8b01072
日期:2018.6.1
The combination of a Pd(0) complex with benzoic acid converts propargylic tryptamines to the corresponding tetrahydro-β-carbolines. The method uses unprotected indoles and affords the desired products with ample functional group tolerance. Detailed modeling studies reveal a close synergy between the organic and metal catalysts, which enables sequential alkyne isomerization, indole C–H activation, and
Alkene <i>versus</i> alkyne reactivity in unactivated 1,6-enynes: regio- and chemoselective radical cyclization with chalcogens under metal- and oxidant-free conditions
作者:Mohana Reddy Mutra、Vishal Suresh Kudale、Jing Li、Wu-Hsun Tsai、Jeh-Jeng Wang
DOI:10.1039/d0gc00321b
日期:——
light-promoted alkene vs. alkyne regio- and chemoselective radical cascade cyclization of electronically unbiased 1,6-enynes with chalcogens to synthesize substituted pyrrolidines bearing chalcogens. The reaction generated three new bonds, namely, C–SO2, C–C, and C–Se under extremely mild conditions. Furthermore, we achieved regio- and chemoselective mono-addition of aromatic thiophenols with unactivated 1,6-enynes
Potassium <i>tert</i>-Butoxide Promoted Annulation of 2-Alkynylphenyl Propargyl Ethers: Selective Synthesis of Benzofuran and 12<i>H</i>-Benzoannulene Derivatives
作者:Tamiris B. Grimaldi、Davi F. Back、Gilson Zeni
DOI:10.1021/jo4020062
日期:2013.11.1
We present here our results on potassiumtert-butoxide promoted annulation reactions of 2-alkynylphenyl propargyl ethers to give two different types of heterocycles: 3-benzyl-2-alkynylbenzofurans and 12H-benzoannulenbenzo[b]furans. A series of functionalized 2-alkynylphenyl propargyl ethers were efficiently cyclized by potassiumtert-butoxide to the corresponding products. The optimized reaction conditions
我们在这里介绍关于叔丁醇钾促进的2-炔基苯基炔丙基醚的环化反应以产生两种不同类型的杂环的结果:3-苄基-2-炔基苯并呋喃和12 H-苯并环戊并苯并[ b ]呋喃。叔丁基钾有效地环化了一系列官能化的2-炔基苯基炔丙基醚-丁氧化物制得相应产物。优化的反应条件可耐受多种官能团,包括富电子,贫电子和N杂环底物。通过控制溶剂和温度获得选择性的产物形成。当在室温下使用THF时,只能获得3-苄基-2-炔基苯并呋喃衍生物,而在60°C下使用DMF时,则可以选择性地生成12 H-苯并环戊烯[ b ]苯并呋喃。