Stereoselective Olefination of N-Sulfonyl Imines with Stabilized Phosphonium Ylides for the Synthesis of Electron-Deficient Alkenes
作者:Fan Fang、Yuan Li、Shi-Kai Tian
DOI:10.1002/ejoc.201001379
日期:2011.2
alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphoniumylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphoniumylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphoniumylides afford α,β-unsaturated esters, amides
已经开发了一种前所未有的方案,用于从易于获得的 N-磺酰基亚胺和稳定的鏻叶立德以中等至优异的产率立体选择性合成结构多样的缺电子烯烃。值得注意的是,N-磺酰亚胺与腈稳定的鏻叶立德的烯化反应提供了一系列具有高 Z 选择性的 α,β-不饱和腈,并且与酯、酰胺和酮稳定的鏻叶立德的反应提供了 α,β -分别具有高 E 选择性的不饱和酯、酰胺和酮。反应混合物的光谱分析和中间体的捕获允许提出合理的机制。初始亚胺/叶立德加成导致形成环化形成 1 的甜菜碱,2-氮杂膦烷随后消除亚氨基膦以产生烯烃。对于缺电子的 1,2-二取代烯烃的合成,甜菜碱中吸电子基团的存在允许通过质子转移在其两种非对映异构体之间快速相互转化。烯烃合成的 Z/E 选择性由两种甜菜碱非对映异构体形成相应的 1,2-氮杂膦非对映异构体的不同速率决定。相比之下,合成缺电子三取代烯烃的 Z/E 选择性源于稳定的鏻叶立德与 N-磺酰基亚胺的非对映选
Chemoselective efficient synthesis of functionalized β-oxonitriles through cyanomethylation of Weinreb amides
作者:Ashenafi Damtew Mamuye、Laura Castoldi、Ugo Azzena、Wolfgang Holzer、Vittorio Pace
DOI:10.1039/c4ob02398f
日期:——
Homologation of Weinreb amides with cyanomethyllithium: a new route to β-oxonitriles.
Weinreb酰胺与氰甲基锂的同源化反应:β-氧代腈的新途径。
Synthesis of α,β-Unsaturated α′-Haloketones through the Chemoselective Addition of Halomethyllithiums to Weinreb Amides
作者:Vittorio Pace、Laura Castoldi、Wolfgang Holzer
DOI:10.1021/jo401236t
日期:2013.8.2
A straightforward synthesis of variously functionalized α,β-unsaturated α′-haloketones has been achieved through the chemoselective addition of halomethyllithium carbenoids to Weinrebamides at −78 °C. A comparative study employing the corresponding esters under the same reaction conditions pointed out that the instability of the tetrahedral intermediate formed from the latter is responsible for the
作者:Wei He、Jie Huang、Xiufeng Sun、Alison J. Frontier
DOI:10.1021/ja0761986
日期:2008.1.1
The totalsynthesis of racemic merrilactone A (a neurotrophic agent) is described, featuring simultaneous and stereospecific creation of the C4 and C5 stereocenters via a notable silyloxyfuran Nazarov cyclization. Full details of the successful synthetic strategy are given, as well as several examples of the interesting reactivity of intermediates that were prepared and studied during the execution
Stereoselective Iridium-N,P-Catalyzed Double Hydrogenation of Conjugated Enones to Saturated Alcohols
作者:Bram B. C. Peters、Jia Zheng、Suppachai Krajangsri、Pher G. Andersson
DOI:10.1021/jacs.2c02422
日期:2022.5.18
multitude of catalytic systems have been developed for this purpose. However, due to the different nature of the π-system, the hydrogenation of olefins and ketones is normally catalyzed by different metal complexes. Herein, a study on the effect of additives on the Ir-N,P-catalyzed hydrogenation of enones is described. The combination of benzamide and the development of a reactive catalyst unlocked a