Cascade Reactions: Sequential Homobimetallic Catalysis Leading to Benzofurans and β,γ-Unsaturated Esters
作者:Bartolo Gabriele、Raffaella Mancuso、Giuseppe Salerno、Mirco Costa
DOI:10.1002/adsc.200606037
日期:2006.6
what we have named “sequentialhomobimetalliccatalysis”) has been shown to occur starting from 1-(2-allyloxyphenyl)-2-yn-1-ols 1 to afford 2-benzofuran-2-ylacetic esters 2 and β,γ-unsaturatedesters in high yields under carbonylative conditions. In view of the conceptual as well as the synthetic importance of the process, the mechanistic aspects and the synthetic scope of the reaction have been investigated
Lewis Acid Catalyzed Tandem 1,4-Conjugate Addition/Cyclization of in Situ Generated Alkynyl <i>o</i>-Quinone Methides and Electron-Rich Phenols: Synthesis of Dioxabicyclo[3.3.1]nonane Skeletons
作者:Ji-Yuan Du、Yan-Hua Ma、Fan-Xiao Meng、Bao-Li Chen、Shao-Liang Zhang、Qian-Li Li、Shu-Wen Gong、Da-Qi Wang、Chun-Lin Ma
DOI:10.1021/acs.orglett.8b01862
日期:2018.7.20
A versatile Lewis acid catalyzed tandem cyclization of in situgenerated alkynyl o-quinone methides (o-AQMs) with electron-rich phenols has been developed on the basis of the mode involving an intermolecular 1,4-conjugate addition/6-endo cyclization/1,3-aryl shift/intramolecular 1,4-conjugate addition cascade. This reaction provides a new method for expeditious assembly of synthetically and biologically
yields in a totally selective manner. In this way, bis(triflyl)flavones, bis(triflyl)thioflavones, bis(triflyl)selenoflavones, (triflyl)benzothienopyrans, (triflyl)benzoselenophenopyrans, (triflyl)vinyl aurones, and (triflyl)pyranoindoles were constructed. Conceivable mechanistic pathways were suggested on the basis of the isolation of several intermediates and the results from control experiments
可以通过Tf 2 C = CH 2激活功能化的炔酮,原位生成,形成两性离子物质。这些物种以分子内方式被数个亲核试剂捕获,以发散的方式产生两种主要类型的三苯甲酮。通过对反应温度的微调,以完全选择的方式以合理的收率获得了双(triflyl)-6元或(triflyl)-5元稠合杂环。以此方式,构建了双(三氟乙)黄酮,双(三氟乙)硫代黄酮,双(三氟乙)硒代黄酮,(三氟乙)苯并噻吩并吡喃,(三氟苯)苯并硒基苯并吡喃,(三氟乙)乙烯基金酮和(三氟乙)吡喃并吲哚。根据几种中间体的分离和对照实验的结果,提出了可能的机理途径。
Ligand-Promoted, Copper Nanoparticles Catalyzed Oxidation of Propargylic Alcohols with TBHP or Air as Oxidant
作者:Xiaoquan Yao、Chengyan Han、Min Yu、Weijiang Sun
DOI:10.1055/s-0030-1261227
日期:2011.10
A highly efficient oxidation of propargylicalcohols to ynones was catalyzed by copper nanoparticles (Cu Nps) with TBHP as an oxidant at room temperature. With bipyridine as the ligand, the reaction was accelerated significantly and led in good to excellent yields to a variety of propargylicalcohols. Furthermore, with Cu Nps as the catalyst, molecular oxygen in air could be utilized as oxidant effectively
An environmentally benign protocol that affords propargylic sulfones containing highly congested carbon centers from easily accessible alcohols and sulfinic acids with water as the only byproduct is reported. The reaction proceeded via an in situ dehydrative cross-coupling process by taking advantage of the synergetic actions of multiple hydrogen bonds rather than relying on an external catalyst and/or