An Unprecedented Organocascade Synthesis of Functionalized Bicyclic Nitrones from 2‐Aminomalonate Derived Nucleophiles and 1‐Nitro‐1,3‐Enynes via Allenes Formation and Subsequent Rearrangement
作者:Wan‐Yun Huang、Ramani Gurubrahamam、Kwunmin Chen
DOI:10.1002/adsc.201801161
日期:2019.1.11
An efficient organocatalytic cascade reaction for synthesising functionalized bicyclic nitrones is reported. The reaction of dielectrophilic ethyl 2‐(nitromethylene)‐4‐arylbut‐3‐ynoate and (E)‐diethyl 2‐((2‐hydroxybenzylidene)‐amino)malonates to give a unique nitrone scaffold in the presence of a catalytic amount of DABCO is described. The working mechanism was proposed to proceed with allene formation
Three-Component Assembly and Divergent Ring-Expansion Cascades of Functionalized 2-Iminooxetanes
作者:Weijun Yao、Lianjie Pan、Yiping Zhang、Gang Wang、Xiaoqin Wang、Cheng Ma
DOI:10.1002/anie.201004685
日期:2010.11.22
A bold diversification strategy: Aromatic alkynes, p‐toluenesulfonyl azide, and aromatic 2‐oxobut‐3‐ynoates underwent a copper(I)‐catalyzed multicomponent reaction to provide functionalized 2‐iminooxetanes 1, which could be converted selectively into five‐membered nitrogen‐containing heterocycles of two different sorts, depending on the reaction conditions (see scheme; Tf=trifluoromethanesulfonyl;
大胆的多元化战略:芳烃,对甲苯磺酰叠氮化物和芳族2-氧代丁3酸酯进行铜(I)催化的多组分反应,以提供功能化的2-亚氨基氧杂环丁烷1,可以选择性地将其转化为五元氮取决于反应条件(参见方案; Tf =三氟甲磺酰基; R = Et,i Pr)包含两种不同类型的杂环。
Asymmetric Catalytic Synthesis of Epoxides via Three-Component Reaction of Diazoacetates, 2-Oxo-3-ynoates, and Nitrosoarenes
An enantioselective three-componentreaction of diazoacetates, 2-oxo-3-ynoates, and nitrosoarenes has been developed by using a chiral N,N′-dioxide/Ni(OTf)2 complex. This catalytic manifold allows rapid access to a series of multifunctional chiral epoxides containing an imino ketone substituent in moderate to good yields (up to 82%) and excellent diastereo- and enantioselectivities (up to >95/5 dr
通过使用手性N,N'-二氧化物/ Ni(OTf)2络合物,已开发出重氮乙酸酯,2-氧代-3-炔酸酯和亚硝基芳烃的对映选择性三组分反应。该催化歧管允许以中等到良好的收率(高达82%)以及出色的非对映和对映选择性(高达> 95/5 dr和99%ee)快速访问一系列含有亚氨基酮取代基的多功能手性环氧化物。在温和的反应条件下,Z / E比的水平(高达> 95/5 Z / E)。
Organocatalytic synthesis of densely functionalized oxa-bridged 2,6-epoxybenzo[<i>b</i>][1,5]oxazocine heterocycles
Metal-free addition of salicylhydrazones to electron deficient internal alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles was achieved. The demonstrated protocol proceeds through an o-quinone methide formation, aza-Michael addition, stereoselective protonation, enamine promoted aromatization, O,O-acetalization and O,N-aminalization
实现了在1,4-二氮杂双环[2.2.2]辛烷(DABCO)催化下,将水杨酰肼无金属加成至缺电子的内部炔烃中,从而生成氧杂桥联的2,6-环氧苯并[ b ] [1,5]恶唑啉杂环。所证明的方案通过邻醌甲基化物的形成,氮杂-迈克尔加成,立体选择性质子化,烯胺促进的芳构化,O,O-乙缩醛化和O,N-酰胺化序列进行,以高产率提供具有高非对映选择性的特权杂环。
Enantioselective aza‐Friedel‐Crafts Reaction of Heteroarenes with in situ Generated Isoxazolium Ions via Chiral Phosphoric Acid Catalysis
An asymmetricorganocatalyticaza-Friedel-Craftsreaction was developed to give the enantioenriched Δ4-isoxazoline scaffold bearing a quaternary-substituted stereogenic centre in good-to-excellent yields and enantioselectivity (50–99%, 55–>99% ee). This protocol involves the in situ generated isoxazolium ions in the presence of a chiral phosphoric acid followed by the heteroarene addition through asymmetric