Herein we report a novel palladium-catalyzedoxidativecarbonylation reaction for the synthesis of phthalimides with high atom- and step-economy. In our strategy, the imine and H2O, which are generated in situ from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available
Chemoselective Cross-Coupling between Two Different and Unactivated C(aryl)–O Bonds Enabled by Chromium Catalysis
作者:Jinghua Tang、Liu Leo Liu、Shangru Yang、Xuefeng Cong、Meiming Luo、Xiaoming Zeng
DOI:10.1021/jacs.0c00283
日期:2020.4.29
combination of low-cost Cr(II) salt, 4,4-di-tert-butyl-2,2-dipyridyl (dtbpy) ligand and magnesium reductant shows high reactivity in promoting the reductive cross-coupling of aryl methyl ether derivatives with aryl esters, by cleavage and coupling of two different C(aryl)-O bonds undermildconditions. The formation of active low-valent Cr species by reduction of CrCl2 with Mg can be considered, which prefers
Reductive cleavage of aromatic and benzylic C–O bonds by chromium catalysis is reported. This deoxygenative reaction was promoted by low-cost CrCl2 precatalyst combined with poly(methyl hydrogen siloxane) as the mild reducing agent, providing a strategy in forming reduced motifs by cleavage of unactivated C–O bonds. A range of functional groups such as bromide, chloride, fluoride, hydroxyl, amino,
Regio- and Chemoselective Kumada–Tamao–Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium Under Mild Conditions
作者:Xuefeng Cong、Huarong Tang、Xiaoming Zeng
DOI:10.1021/jacs.5b08621
日期:2015.11.18
the cross-coupling reactions with arylethers via C-O bond activation have attracted broad interest. However, the functionalizations of C-O bonds are mainly limited to nickel catalysis, and selectivity has long been a prominent challenge when several C-O bonds are present in the one molecule. We report here the first chromium-catalyzed selective cross-coupling reactions of arylethers with Grignard reagents
作为一种环境友好的合成工具,通过 CO 键活化与芳基醚的交叉偶联反应引起了广泛的兴趣。然而,CO 键的功能化主要限于镍催化,当一个分子中存在多个 CO 键时,选择性一直是一个突出的挑战。我们在这里报告了第一个铬催化的芳基醚与格氏试剂通过 CO(烷基)键断裂的选择性交叉偶联反应。在室温下使用简单、廉价的铬 (II) 预催化剂结合亚氨基助剂实现了多种转化。它为高效和选择性地构建官能化芳香醛提供了新途径。
Cascade C–H Annulation of Aldoximes with Alkynes Using O<sub>2</sub> as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons
作者:Junbin Tang、Shiqing Li、Zheng Liu、Yinsong Zhao、Zhijie She、Vilas D. Kadam、Ge Gao、Jingbo Lan、Jingsong You
DOI:10.1021/acs.orglett.6b03772
日期:2017.2.3
also achieved under slightly modified conditions. This protocol provides an efficient one-pot access to multisubstituted dehydroberberinium skeletons from simple starting materials, which can be easily transformed into berberinium and tetrahydroberberine skeletons by controlled hydrogenation.
在存在氧的Zn(OTf)2存在下,通过使用简单的[Cp * Rh(OAc)2 ] 2催化体系,开发了醛肟与炔烃的级联双CH环化反应以生产苯并[ a ] ac啶鎓盐。唯一的氧化剂。此外,在稍加修饰的条件下,醛基肟与炔烃,特别是芳基炔烃的CH环化反应也难以合成1 H-异喹啉。该协议提供了从简单的起始原料到多取代脱氢小in碱骨架的有效一锅通行方式,可以通过控制加氢将其轻松转化为小ber碱和四氢小ber碱骨架。