C-H insertion. By employing chiral diphenylethylene diamine (dpen) as ligands bearing electron-withdrawing arylsulfonyl substituents, the reactions occur with remarkable chemo- and enantioselectivities; the competing Curtius-type rearrangement was largely suppressed. Enantioselective nitreneinsertion to allylic/propargylic C-H bonds was also achieved with remarkable tolerance to the C═C and C≡C bonds
Efficient Copper-Catalyzed Multicomponent Synthesis of <i>N-</i>Acyl Amidines via Acyl Nitrenes
作者:Kaj M. van Vliet、Lara H. Polak、Maxime A. Siegler、Jarl Ivar van der Vlugt、Célia Fonseca Guerra、Bas de Bruin
DOI:10.1021/jacs.9b07140
日期:2019.9.25
Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper-catalyzed three-component reaction of aryl acetylenes, amines, and easily accessible
enantioselective C(sp3)-H functionalization reactions are still highly desirable. In particular, the ability to use attractive noncovalent interactions for rate acceleration and enantiocontrol would significantly expand the current arsenal for asymmetric metal catalysis. Herein, we report the development of a highly enantioselective Ir(III)-catalyzed intramolecular C(sp3)-H amidation reaction of dioxazolone
尽管在过去十年中取得了显着进展,但在对映选择性 C(sp3)-H 官能化反应中手性催化剂的新设计策略仍然是非常需要的。特别是,使用有吸引力的非共价相互作用进行速率加速和对映控制的能力将显着扩展不对称金属催化的当前武器库。在此,我们报告了高对映选择性 Ir(III) 催化的二恶唑酮底物的分子内 C(sp3)-H 酰胺化反应的开发,该反应用于使用新设计的基于 α-氨基酸的手性配体合成光学富集的 γ-内酰胺。这种 Ir 催化的反应在非常温和的条件下以优异的效率进行,并对活化和未活化的烷基 C(sp3)-H 键具有出色的对映选择性。它为γ-烷基γ-内酰胺的不对称合成提供了第一条通用路线。发现水是一种独特的共溶剂,可在 γ-芳基内酰胺生产中实现出色的对映选择性。机理研究表明,配体在 Ir 中心周围形成了一个明确的凹槽型手性袋。该口袋的疏水作用允许在极性或水性介质中轻松立体控制底物结合。这种新的 Ir
P(III)‐Assisted Electrochemical Access to Ureas via in situ Generation of Isocyanates from Hydroxamic Acids
作者:Haiwen Meng、Kunhui Sun、Zhimin Xu、Lifang Tian、Yahui Wang
DOI:10.1002/ejoc.202100113
日期:2021.3.19
P(III)‐assisted electrochemical generation of isocyanates from hydroxamic acids was successfully applied in the synthesis of ureas. Hydroxamic acids were directly used without pre‐activation, and the reaction was found not sensitive to water or air. The process started with the anodic oxidation of hydroxamic acids, followed by reacting with trivalent phosphine to form corresponding alkoxyphosphoniums
Tethered Aminohydroxylation (TA) Reaction of Amides
作者:Timothy J. Donohoe、Cedric K. A. Callens、Amber L. Thompson
DOI:10.1021/ol900631y
日期:2009.6.4
The first examples of amide-tethered aminohydroxylationreactions, catalyzed by osmium, showing that the use of N−O-based reoxidants are essential for success, are reported. The system that is described is compatible with a variety of different alkene substitution patterns and ring sizes and works with low loadings in both cyclic and acyclic systems. The levels of diastereoselectivity that were observed