Catalytic Transformations of Alkynes into either α-Alkoxy or α-Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile-Directed Chemoselectivity
作者:Rajkumar Lalji Sahani、Manoj D. Patil、Sachin Bhausaheb Wagh、Rai-Shung Liu
DOI:10.1002/anie.201806883
日期:2018.11.5
The catalytic formation of gold enolatesfrom alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile‐directed chemoselectivity through cooperative catalysis. For 1‐alkyn‐4‐ols and 2‐ethynylphenols, their gold‐catalyzed nitrone oxidations afforded N‐containing dihydrofuran‐3(2H)‐ones with syn selectivity. The mechanism involves the Mannich reactions of gold
Silver-catalyzed synthesis of 4-substituted benzofurans<i>via</i> a cascade oxidative coupling-annulation protocol
作者:Yang Ye、Renhua Fan
DOI:10.1039/c1cc10137d
日期:——
A facile synthesis of 4-indole benzofurans via an oxidative dearomatization, a silver-catalyzed cascade Michael addition-annulation, and an aromatization is reported.
通过氧化脱芳构建的银催化级联迈克尔加成-环化和芳香化,报告了一种简便的4-吲哚苯并呋喃合成。
Oxyacylation of Iodoalkynes: Gold(I)-Catalyzed Expeditious Access to Benzofurans
作者:Paula Fernández-Canelas、Eduardo Rubio、José M. González
DOI:10.1021/acs.orglett.9b02551
日期:2019.8.16
6-diisopropylphenyl)-imidazole-2-ylidene] gold(I) catalyzes the cycloisomerization of 2-(iodoethynyl)aryl esters to give 3-iodo-2-acyl benzofurans. This catalytic transformation is the result of an unprecedented selective synthetic event, which comprises a [1,2]-iodine shift, a C–O ring-closure step, and a C–C bond-formation that installs the ketone functionality into the new ring. Experimental evidence
Direct Assembly of 3,4-Difunctionalized Benzofurans and Polycyclic Benzofurans by Phenol Dearomatization and Palladium-Catalyzed Domino Reaction
作者:Zhaomeng Han、Liang Zhang、Zhiming Li、Renhua Fan
DOI:10.1002/anie.201404155
日期:2014.6.23
A method to directly convert 2‐alkynylphenols to 3,4‐difunctionalized benzofurans and polycyclic benzofurans was developed. This protocol involves a hypervalent‐iodine‐mediated oxidative dearomatization to break the aromaticity of 2‐alkynylphenols, and a palladium‐catalyzed domino reaction to install two functional groups at the C3 and the C4 positions and restore the aromaticity of benzofurans.
Intramolecular activation of strong Si–O bonds by gold(<scp>i</scp>): regioselective synthesis of 3-bromo-2-silylbenzofurans
作者:Paula Fernández-Canelas、Rubén Miguélez、Eduardo Rubio、José Manuel González、Pablo Barrio
DOI:10.1039/d2cc03060h
日期:——
of one of the strongest bonds in organic chemistry (Si–O), strategically placed at the ortho-position. In this way, the synthesis of 3-bromo-2-silylbenzofuranes is achieved in good yields. Several substituents with different electronic properties and substitution patterns are well tolerated on the tethering aromatic ring as well as a number of silyl groups on the O-atom. A preliminary mechanistic study
金-亚乙烯基配合物的高反应性,由相应的 1-溴炔烃的 [1,2]-溴转移原位产生,允许激活有机化学中最强的键之一 (Si-O),战略性地放置在邻位。这样,3-溴-2-甲硅烷基苯并呋喃的合成以良好的收率实现。几个具有不同电子特性和取代模式的取代基在束缚芳环上以及在 O 原子上的许多甲硅烷基上都具有良好的耐受性。初步的机理研究与金亚乙烯基中间体的参与是相容的。通过正交C-C键形成转化初步展示了所得支架的合成适用性。