Pd-Catalyzed Coupling of Thioamides with <i>N</i>-Tosylhydrazones/Trapping by Esters Cascade Reaction
作者:Zhongliang Cai、Zhi Yao、Liqin Jiang
DOI:10.1021/acs.orglett.0c03796
日期:2021.1.15
N,N-Disubstituted thioamides coupled with N-tosylhydrazones under Pd(TFA)2/tBuXPhos catalyst and NaOtBu, and the intermediates from palladium carbene migratory insertion containing β-hydrogen were trapped by intramolecular esters activated by BF3·Et2O instead of undergoing β-H elimination, providing polyfunctional thiophen-3(2H)-ones with sulfur-containing tetrasubstituted carbon centers in moderate
在Pd(TFA)2 / t BuXPhos催化剂和NaO t Bu催化下,N,N-二取代硫代酰胺与N-甲苯磺酰coupled偶合,以及含β-氢的钯卡宾迁移插入的中间体被BF 3 ·Et 2活化的分子内酯捕获。O代替β- H消除,提供多官能噻吩-3(2H含硫四取代碳原子的α-酮,产率中等至良好。该反应具有一次操作即可形成三个键,无味,安全且易于获得的底物,广泛的底物范围和出色的官能团耐受性的特点。
Blue light-promoted cyclopropenizations of N-tosylhydrazones in water
Carbene transfer reactions play an important role in the field of organicsynthesis because of their ability to construct a variety of molecules. Herein, we reported on blue light-induced cyclopropenizations of N-tosylhydrazones in water, which avoids the use of expensive metal-based catalysts and toxic organic solvents. This metal-free and operationally simple methodology enable highly efficient cyclopropenizations
Metal‐free photochemical carbene‐transfer reactions of tosylhydrazones were developed under blue light irradiation at room temperature. This reaction constructs C−X (X=C, N, O, S) bonds and cyclopropanes from readily available and stable starting materials.
in good to high yields by coupling N-tosylhydrazones (NTHs) with benzylic phosphates as electrophilic partners. The obtained new catalytic system consisted of PdCl2(CH3CN)2/dppp, LiOtBu as a base, and cyclopentyl methyl ether as a green solvent. In addition, we performed a gram-scale transformation using NTH derivatives and benzylic phosphates having a C sp2–Cl bond. The latter was used as a starting
该研究表明,通过将N-甲苯磺酰腙 (NTH) 与磷酸苄基作为亲电伙伴偶联,可以以良好至高产率获得各种具有高化学选择性的二取代和三取代烯烃。得到的新型催化体系由PdCl 2 (CH 3 CN) 2 /dppp、LiO t Bu为碱、环戊基甲基醚为绿色溶剂组成。此外,我们使用 NTH 衍生物和具有 C sp 2 -Cl 键的苄基磷酸酯进行了克级转化。后者被用作关键中间体进一步后功能化的起点。
Blue light induced [2,3]-sigmatropic rearrangement reactions of tosylhydrazones
Metal-free blue light-mediated [2,3]-sigmatropic rearrangement reactions of tosylhydrazones and sulfides are reported herein. This strategy shows great enhancement compared to the traditional methods because of stable starting materials and mild reaction conditions. In this report, we have developed the Doyle-Kirmse reaction and Sommelet-Hauser reaction with simple operation, high yields and broad