Probing the Mechanism of Allylic Substitution of Morita–Baylis–Hillman Acetates (MBHAs) by using the Silyl Phosphonite Paradigm: Scope and Applications of a Versatile Transformation
作者:Maria Kalyva、Alexandros L. Zografos、Era Kapourani、Evaggelos Giambazolias、Laurent Devel、Athanasios Papakyriakou、Vincent Dive、Yannis G. Lazarou、Dimitris Georgiadis
DOI:10.1002/chem.201405626
日期:2015.2.16
using 31P NMR spectroscopy revealedunexpected reactivity differences between ester and nitrile derivatives. These kinetic profiles and DFT calculations support a mechanistic scenario in which observed differences can be explained from the “lateness” of transition states. In addition, we provide experimental evidence suggesting that enolates due to initial P‐Michaeladdition are not formed. Based on
AP 甲硅烷基膦酸酯和森田-的Baylis-希尔曼乙酸盐(MBHAs)之间C键形成反应探索作为向医药相关β-carboxyphosphinic结构基序的通用的替代方案。使用31记录的不同取代的MBHA转化为次膦酸9或14的转化率P NMR光谱显示酯和腈衍生物之间的反应性差异出乎意料。这些动力学曲线和DFT计算支持了一种机械方案,其中可以从过渡态的“迟缓”解释观察到的差异。此外,我们提供的实验证据表明,由于最初的P-Michael加成而形成的烯醇不形成。基于拟议的机械情景结合DFT计算,对E / Z的解释提出了酯和腈之间的立体选择性差异。提出了由这种转变产生的合成机会,该机会涉及几种合成的反复变化的膦基结构单元的制备,而这些结构单元通过经典的P-Michael合成路线的访问并不简单。
Visible-Light-Enabled <i>Ortho</i>-Selective Aminopyridylation of Alkenes with <i>N</i>-Aminopyridinium Ylides
作者:Yonghoon Moon、Wooseok Lee、Sungwoo Hong
DOI:10.1021/jacs.0c05025
日期:2020.7.15
By utilizing an underexplored reactivity mode of N-aminopyridinium ylides, we developed the visible-light-induced ortho-selective aminopyridylation of alkenes via radical-mediated 1,3-dipolar cycloaddition. The photocatalyzed single-electron oxidation of N-aminopyridinium ylides generates the corresponding radical cations that enable previously inaccessible 1,3-cycloaddition with a broader range of
通过利用 N-氨基吡啶鎓叶立德的未充分探索的反应模式,我们通过自由基介导的 1,3-偶极环加成开发了可见光诱导的烯烃邻位选择性氨基吡啶化。N-氨基吡啶鎓叶立德的光催化单电子氧化产生相应的自由基阳离子,使以前无法实现的1,3-环加成与更广泛的烯烃底物成为可能。所得的环加成加合物迅速进行随后的 NN 键均裂,赋予显着的热力学驱动力以产生各种 β-氨基乙基吡啶。值得注意的是,在无金属和温和条件下,氨基和吡啶基可以通过模块化控制邻位选择性和 1,2- 顺式非对映选择性安装到活化和未活化的烯烃中。
Palladium/nickel-mediated cross coupling reaction between phosphorylamides and alkenes toward enephosphorylamides
作者:Zijian Zhao、Qiao Zhu、Shiying Che、Zhenghong Luo、Yan Lian
DOI:10.1080/00397911.2020.1774903
日期:2020.8.2
prepared from phosphorylamides and substituted alkenes. The dehydrogenative transformation took place in the presence of a combination of a palladium diacetate and nickel dichloride. The transition metal-catalyzed methodology enjoyed high efficiency and broad substrate scope. Moreover, a plausible mechanism was proposed for the oxidative C–N cross coupling protocol. Graphical Abstract
A switchable formation of chloro‐ and enephosphorylamides from phosphorylamides and alkenes was disclosed herein. In the presence of Pd(OAc)2, a catalytic loading of CuBr or CuCl2 (20 mol‐%) led to the occurrence of dehydrogenative cross coupling reactions, while 1.0 equivalent of CuCl2 rendered the dehydrogenative amidochlorination reactions to take place in a stereoselective manner.
Size-Exclusion Borane-Catalyzed Domino 1,3-Allylic/Reductive Ireland-Claisen Rearrangements: Impact of the Electronic and Structural Parameters on the 1,3-Allylic Shift Aptitude
reductive Ireland–Claisenrearrangement through borane‐mediated hydrosilylation is reported. The method employs a borane catalyst with a special structural design and affords access to synthetically relevant products with high diastereoselectivity. Depending on electronic and structural parameters, the reaction can be coupled with a 1,3‐allylic shift, thus the valence isomer of the Ireland–Claisen product