Metal-Free Oxidative Cyclization of Alkynyl Aryl Ethers to Benzofuranones
作者:Katharina Graf、Carmen L. Rühl、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/anie.201304813
日期:2013.11.25
Readily available phenols can be converted into substituted arylalkynylethers, which react with an N‐oxide as an oxidant and catalytic amounts of a Brønsted acid to provide benzofuranones. If non‐terminal alkynylethers are applied, a 1,2‐hydride shift takes place and phenyl acrylates are obtained. Thus activated alkynes can serve as α‐oxy carbene precursors even in the absence of a metal catalyst
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
Rhodium-Catalyzed Intermolecular [2+2+2] Cross-Trimerization of Aryl Ethynyl Ethers and Carbonyl Compounds To Produce Dienyl Esters
作者:Yuta Miyauchi、Masayuki Kobayashi、Ken Tanaka
DOI:10.1002/anie.201105519
日期:2011.11.11
thinking: A cationic rhodium(I)/H8‐binap complex catalyzes the chemo‐, regio‐, and stereoselective completely intermolecular [2+2+2] cross‐trimerization of two aryl ethynyl ethers with both electron‐deficient and electron‐rich carbonylcompounds (see scheme; cod=1,5‐cyclooctadiene). This reaction proceeded at room temperature to give aryloxy‐substituted dienyl esters in good yields.
积极思考:阳离子铑(I)/ H 8联键配合物催化两种带有电子缺陷和电子缺陷的芳基乙炔基醚的化学,区域和立体选择性完全分子间[2 + 2 + 2]交叉三聚。富含羰基的化合物(参见方案; cod = 1,5-环辛二烯)。该反应在室温下进行,以良好的收率得到芳氧基取代的二烯基酯。
Synthesis of Cyclobutanones by Gold(I)-Catalyzed [2 + 2] Cycloaddition of Ynol Ethers with Alkenes
作者:Margherita Zanini、Andrea Cataffo、Antonio M. Echavarren
DOI:10.1021/acs.orglett.1c03499
日期:2021.11.19
A broad scope synthesis of cyclobutanones by gold(I)-catalyzed [2 + 2] cycloaddition of ynol ethers with alkenes has been developed. We also found that internal aryl ynol ethers can undergo (4 + 2) cycloaddition reaction with alkenes leading to the corresponding chromanes.
We have established that a cationic rhodium(I)-H8-BINAP complex catalyzes the complete intermolecular homo-[2+2+2] cycloaddition of aryl ethynyl ethers and cross-[2+2+2] cycloaddition of aryl ethynyl ethers with electron-deficient monoalkynes, leading to tri- and diaryloxybenzenes, respectively, at room temperature.