Herein we describe an iron-catalyzed borylation of alkenyl and arylcarbamatesthrough the activation of a C–O bond. This protocol exhibits high efficiency, a broad substrate scope, and the late-stage borylation of biorelevant compounds, thus providing potential applications in medicinal chemistry. Moreover, this method enables orthogonal transformations of phenol derivatives and also offers good opportunities
在本文中,我们描述了通过C-O键的活化,铁催化的烯基和芳基氨基甲酸酯的硼酸酯化反应。该方案显示出高效率,广泛的底物范围以及生物相关化合物的后期硼化,因此在药物化学中提供了潜在的应用。而且,该方法能够使酚衍生物进行正交转化,并且还为合成多取代的芳烃提供了良好的机会。初步的机理研究表明,通过自由基途径的Fe II / Fe III催化循环可能与反应有关。
Air‐Stable Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>‐EDTA‐Ni(0) as an Efficient Recyclable Magnetic Nanocatalyst for Effective Suzuki‐Miyaura and Heck Cross‐Coupling via Aryl Sulfamates and Carbamates
The synthesis of inexpensive and novel air‐stable Ni(0) nanoparticles immobilized on the EDTA‐modified Fe3O4@SiO2 nanocatalyst was investigated in Suzuki‐Miyaura and Heckcross‐couplingreactions. This catalytic system displayed a greatly improved substrate scope for the carbon–carbon bond formations starting from a wide range of green and economical electrophiles aryl and heteroaryl carbamates and
廉价且新颖的,稳定的,稳定在EDTA修饰的Fe 3 O 4 @SiO 2上的Ni(0)纳米颗粒的合成在Suzuki-Miyaura和Heck交叉偶联反应中研究了纳米催化剂。该催化体系通过在温和,操作简单的反应条件下通过高效方法,从广泛的绿色和经济亲电氨基甲酸酯和杂芳基氨基甲酸酯和氨基磺酸盐开始,显着改善了碳-碳键形成的底物范围。合成的多相催化剂还通过FT-IR,TEM,XRD,DLS,FE-SEM,UV-Vis,EDX,XPS,TGA,NMR,VSM,ICP和元素分析技术进行了全面表征。可以通过外部磁场容易地回收异质磁性纳米催化剂,并且在催化剂的沥滤可忽略不计并且活性没有实质性降低的情况下,至少七次重复用于接下来的反应至少七次。所有这些亮点使本协议变得有趣,
Nickel-Catalyzed Amination of Aryl Sulfamates and Carbamates Using an Air-Stable Precatalyst
作者:Liana Hie、Stephen D. Ramgren、Tehetena Mesganaw、Neil K. Garg
DOI:10.1021/ol301847m
日期:2012.8.17
A facile nickel-catalyzed method to achieve the amination of synthetically useful arylsulfamates and carbamates is reported. Contrary to most Ni-catalyzed amination reactions, this user-friendly approach relies on an air-stable Ni(II) precatalyst, which, when employed with a mild reducing agent, efficiently delivers aminated products in good to excellent yields. The scope of the method is broad with
报道了一种简便的镍催化方法来实现合成有用的氨基磺酸芳基酯和氨基甲酸酯的胺化。与大多数 Ni 催化的胺化反应相反,这种用户友好的方法依赖于空气稳定的 Ni(II) 预催化剂,当它与温和的还原剂一起使用时,可以有效地以良好到优异的产率提供胺化产物。该方法的范围就两个偶联伙伴而言都是广泛的,并且包括杂环底物。
The directed ortho-lithiation of aryl tetramethylphosphorodiamidates.
Aryl tetramethylphosphorodiamidates were effectively ortho-lithiated with sec-BuLi in tetrahydrofuran at -105°C.The resulting lithiated species were trapped with a variety of electrophiles at -105°C to provide ortho-substituted phosphorodiamidates. When the lithiation was carried out at -78°C, O→C migration of the bis(dimethylamino)phosphoryl group took place rapidly and 2-hydroxyarylphosphonic tetramethyldiamides were produced regioselectively. The ortho-directing ability of the phosphorodiamidates was investigated by intermolecular competition experiments with other directed metalation groups.
The reactions of o-lithiated O-aryl N,N-diethylcarbamates with different C–N multiple bond electrophiles have been thoroughly studied. A 1,5-O → N carbamoyl shift, a new variation of the anionic Fries-type rearrangement, takes place when nitriles, imines, or alkylcarbodiimides are employed. In these cases, the carbamoyl group plays a dual role as a directing group, building up a variety of functional