Tandem cross-Rauhut–Currier/cyclization reactions of activated alkenes to give densely functionalized 3,4-dihydropyrans
摘要:
A novel tandem cross-Rauhut-Currier/cyclization reaction between alpha,beta-unsaturated ketones was developed. Using DABCO (20 mol %) as the catalyst, a series of densely functionalized 3,4-dihydropyrans were obtained in excellent yields and stereoselectivities (up to 98% yield, >99:1 dr). A tentative catalytic cycle was proposed with key intermediates confirmed by ESIMS studies. (C) 2011 Elsevier Ltd. All rights reserved.
Substituent‐Controlled Divergent Cascade Cycloaddition Reactions of Chalcones and Arylalkynols: Access to Spiroketals and
<i>Oxa</i>
‐Bridged Fused Heterocycles
作者:Tianlong Zeng、Jingyang Kong、Hongkai Wang、Lingyan Liu、Weixing Chang、Jing Li
DOI:10.1002/adsc.202100523
日期:2021.8.13
Herein, we report substituent-controlled divergentcascadecycloadditionreactions of chalcones and arylalkynols in the presence of PtI2. Depending on the substituent on the chalcone, either spiroketals or oxa-bridged fusedheterocycles could be obtained in the ranges of 86–97% and 87–95% yields under identical reaction conditions. Control experiments were carried out to elucidate the origin of the
Organocatalytic Asymmetric [4+2] Cycloaddition of 1-Acetylcyclopentene and 1-Acetylcyclohexene for the Synthesis of Fused Carbocycles
作者:Utpal Nath、Subhas Chandra Pan
DOI:10.1002/ejoc.201701238
日期:2017.11.24
The first organocatalytic asymmetric [4+2] cycloaddition reaction employing 1-acetylcyclopentene and 1-acetylcyclohexene is described. Enones having cyano group are used as the dienophile partner in this method. The reaction provides a useful practical route for the synthesis of bicyclic fused carbocycles having four contiguous stereocentres.
Activated Nitriles in Heterocyclic Synthesis. Synthesis of Pyrimidine Derivatives
作者:Kamal Usef Sadek、Mohamed Abdallah El-Maghraby、Maghraby Ali Selim、Mohamed Hilmy Elnagdi
DOI:10.1246/bcsj.61.539
日期:1988.2
Synthesis of polyfunctional pyrimidinederivatives via the reaction of acrylonitrile derivatives 1a and b with α,β-unsaturated nitriles 2a–f has been reported.
已经报道了通过丙烯腈衍生物 1a 和 b 与 α,β-不饱和腈 2a-f 反应合成多官能嘧啶衍生物。
Enantioselective Addition-Alkylation of α,β-Unsaturated Carbonyls via Bisguanidinium Silicate Ion Pair Catalysis
作者:Wenchao Chen、Esther Cai Xia Ang、Siu Min Tan、Zhijie Chua、Jingyun Ren、Ziqi Yang、Bo Teng、Richmond Lee、Haihua Lu、Choon-Hong Tan
DOI:10.1021/jacs.0c00183
日期:2020.11.11
Silicon hydrides, alkynylsilanes, and alkoxylsilanes were activated by fluoride in the presence of bisguanidinium catalyst to form hypervalent silicate ionpairs. These activated silicates undergo 1,4-additions with chromones, coumarins, and α-cyanocinnamic esters generating enolsilicate intermediates, for a consequent stereoselective alkylation reaction. The reduction-alkylation reaction proceeded
Preparation of Tetrasubstituted Furans via Intramolecular Wittig Reactions with Phosphorus Ylides as Intermediates
作者:Tzu-Ting Kao、Siang-en Syu、Yi-Wun Jhang、Wenwei Lin
DOI:10.1021/ol101080q
日期:2010.7.2
functional furans can be efficiently generated in one step at room temperature within 10 min to 21 h in moderate to high yields (60−99%). The reaction was proposed to proceed via intramolecular Wittig-type reactions, using phosphorus ylides as intermediates.