Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO: reaction development and application to the formal synthesis of (−)-galanthamine
作者:Cheng-Hang Liu、Zhi-Xiang Yu
DOI:10.1039/c6ob00660d
日期:——
A Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO has been developed to synthesize functionalized 2-methylidene-3,4-cyclohexenones. The scope of this methodology has been investigated, showing that various functional groups can be tolerated. Both di- and tri-substituted allenylcyclopropanes can be applied to this cycloaddition and the [5 + 1] cycloadducts with the E configuration
Olefin-Migrative Cleavage of Cyclopropane Rings through the Nickel-Catalyzed Hydrocyanation of Allenes and Alkenes
作者:Hiroto Hori、Shigeru Arai、Atsushi Nishida
DOI:10.1002/adsc.201601400
日期:2017.4.3
A nickel‐catalyzed hydrocyanation triggered by hydronickelation of the carbon‐carbon double bonds of allenes followed by cyclopropane cleavage is described. The observed regio‐ and stereochemistries in the products are strongly influenced by the initial hydronickelation step, and allenyl‐ and methylenecyclopropanes reacted smoothly to promote the cleavage of cyclopropane. In contrast, this cleavage
A convenient access to allylic triflones with allenes and triflyl chloride in the presence of (EtO)<sub>2</sub>P(O)H
作者:Jixiang Ni、Yong Jiang、Zhenyu An、Jingfeng Lan、Rulong Yan
DOI:10.1039/c9cc03096d
日期:——
A simple method for the preparation of allylic triflones from allenes and triflyl chloride in the presence of (EtO)2P(O)H has been developed. The features of this reaction are catalyst-free and simple starting substrates. This method tolerates diverse functional groups and substituted allylic triflones are obtained in moderate to good yields.
Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes
作者:Jiawang Liu、Ming Nie、Qinghai Zhou、Shen Gao、Wenhao Jiang、Lung Wa Chung、Wenjun Tang、Kuiling Ding
DOI:10.1039/c7sc01254c
日期:——
A practical and enantioselectivepalladium-catalyzed diboration of 1,1-disubstituted allenes is developed by employing a P-chiral monophosphorus ligand BI-DIME to form a series of diboronic esters containing a chiral tertiary boronic ester moiety in excellent yields and ee’s with the palladium loading as low as 0.2 mol %. DFT calculations revealed a concerted mechanism of oxidative addition of bis(pinacolato)diboron
通过使用 P-手性单磷配体 BI-DIME 开发了一种实用且对映选择性的钯催化 1,1-二取代丙二烯二硼化反应,以形成一系列含有手性叔硼酸酯部分的二硼酸酯,具有优异的产率和与钯的 ee 值负载量低至 0.2 mol%。DFT 计算揭示了双(频哪醇)二硼和丙二烯插入的氧化加成的协同机制,以及对对映选择性起源的关键分散效应。该方法成功应用于芸苔唑的简洁、对映选择性合成。
Electrophilic cyanation of allylic boranes: synthesis of β,γ-unsaturated nitriles containing allylic quaternary carbon centers
The electrophilic cyanation of allylic boranes, a process that is applicable to the construction of allylic quaternary carbon centers, is reported. The reaction has a broad substrate scope with a high functional group tolerance. The results represent an unprecedented and powerful tool for preparing synthetically useful β,γ-unsaturated nitriles, including derivatives that have been difficult to access