报道了在水中表面活性剂的辅助下咪唑并[1,2- a ]吡啶与N-氨基吡啶鎓盐胺化的光促进无金属方案,具有温和和环境友好的条件,以及良好的官能团耐受性. 具有带负电荷的极性表面和由十二烷基硫酸钠形成的疏水核的胶束是可见光介导的阳离子吡啶盐和咪唑并[1,2- a ]吡啶在水相中发生自由基反应的理想介质。带正电荷的N-氨基吡啶鎓与带负电荷的胶束表面之间的静电相互作用在该方法中具有重要意义。
Synthesis of 2- and 2,3-Substituted Pyrazolo[1,5-a]pyridines: Scope and Mechanistic Considerations of a Domino Direct Alkynylation and Cyclization of N-Iminopyridinium Ylides Using Alkenyl Bromides, Alkenyl Iodides, and Alkynes
摘要:
Direct functionalization and tandem processes have both received considerable recent interest due to their cost and time efficiency. Herein we report the synthesis of difficult to obtain 2-substituted pyrazolo[1,5-a]pyridines through a tandem palladium-catalyzed/silver-mediated elimination/direct functionalization/cyclization reaction involving N-benzoyliminopyridinium ylides. As such, these biologically important molecules are prepared in an efficient, high-yielding manner, only requiring a two-step sequence from pyridine. Aryl-substituted alkenyl bromides and iodides are effective ylide coupling partners. Mechanistic studies led to the use of terminal alkynes, which extended the scope of the reaction to include alkyl substitution on the unsaturated reactive site. The optimization, scope, and mechanistic considerations of the process are discussed.
Rh(III)-Catalyzed C–H Diamidation and Diamidation/Intramolecular Cyclization of <i>N</i>-Iminopyridinium Ylides with Dioxazolones
作者:Xiang Li、Qing Zhao、Yang Shen、Ran Ma
DOI:10.1021/acs.joc.1c03042
日期:2022.3.4
A highly efficient Rh(III)-catalyzed C–H diamidation and diamidation/intramolecular cyclization of N-iminopyridinium ylides with dioxazolones has been developed, providing diamidated products and benzoxazinone products in good to excellent yields. Notably, the tunable selectivity of this reaction can be controlled by simply switching the solvent and the temperature. This reaction features operational
Ru(<scp>ii</scp>)-Catalyzed C–H bond activation/annulation of <i>N</i>-iminopyridinium ylides with sulfoxonium ylides
作者:Xiang Li、Danlu Li、Xiaofei Zhang
DOI:10.1039/d1ob02427b
日期:——
A Ru(II)-catalyzed C–H bond activation/annulation of N-iminopyridinium ylides with sulfoxoniumylides has been developed for the synthesis of diverse functionalized isocoumarin derivatives. This method features broad substrate scope, high functional group tolerance, simple operation and silver salt-free conditions. Furthermore, the synthetic utility of this method is demonstrated by the alkenylation
已经开发了一种 Ru( II ) 催化的N-亚氨基吡啶叶立德与锍叶立德的 C-H 键活化/环化,用于合成各种官能化的异香豆素衍生物。该方法具有底物范围广、官能团耐受性高、操作简单、无银盐条件等特点。此外,该方法的合成效用通过产物的烯基化和生物活性 thunberginol A 的有效合成得到证明。
Catalyst Choice for Highly Enantioselective [3 + 3]-Cycloaddition of Enoldiazocarbonyl Compounds
作者:Kostiantyn O. Marichev、Frady G. Adly、Alejandra M. Carranco、Estevan C. Garcia、Hadi Arman、Michael P. Doyle
DOI:10.1021/acscatal.8b03391
日期:2018.11.2
Chiral copper(I) catalysts are preferred over chiral dirhodium(II) catalysts for [3 + 3]-cycloaddition reactions of enoldiazocarbonyl compounds with nitrones and acyliminopyridinium ylides, forming chiral oxazines and pyrazines in very high yield and enantioselectivity. Yields and stereoselectivitiesfrom reactions of enoldiazoketones are virtually the same as those from the corresponding esters and
Visible‐Light‐Promoted Radical Cyclization and N−N Bond Cleavage Relay of N‐Aminopyridinium Ylides for Access to 2,3‐Difunctionalized Indoles
作者:Meng‐Meng Xu、Wen‐Bin Cao、Xiao‐Ping Xu、Shun‐Jun Ji
DOI:10.1002/adsc.202200248
日期:2022.7.5
accurate difunctionalization reaction undergoes a tandem process involving a radical-mediated 1,3-dipolar cycloaddtion which generated from the single-electron oxidation of N-aminopyridinium ylides, a cleavage of the N−N bond as well as an oxidation of indoline ring. The electrophilic pyridyl and nucleophilic amino groups can be installed simultaneously into a wide range of indoles under mild and metal-free