Synthesis of Terminal Allenes through Copper-Mediated Cross-Coupling of Ethyne withN-Tosylhydrazones or α-Diazoesters
摘要:
Ethyne is employed as coupling partner in copper-mediated cross-coupling reactions with N-tosylhydrazones and alpha-diazoacetate, leading to the development of a new synthetic method for terminal allenes. With this novel coupling method, the terminal allenes were obtained in good yields and with excellent functional group tolerance. Copper carbene migratory insertion is proposed as the key step in these transformations.
Palladium(0)‐catalysed hydro‐alkylation or ‐alkenylation of alkoxyallenes with N‐tosylhydrazones gives direct access to conjugated and skipped 1‐alkoxydienes with high efficiency and excellent functional‐group compatibility. The reaction is proposed to involve the in situ‐formed t‐butanol as proton source in the key step of the allylpalladium(II) species generation. Moreover, lithium iodide or iodobenzene
Transition-Metal-Free Synthesis of Pinacol Alkylboronates from Tosylhydrazones
作者:Huan Li、Long Wang、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201108139
日期:2012.3.19
Highly efficient: Pinacolalkylboronates were synthesized by the reaction of tosylhydrazones with bis(pinacolato)diboron or pinacolborane under transition‐metal‐free conditions. This reaction represents an expeditious conversion of carbonyl functionality into a boronate group.
C(sp)–C(sp<sup>3</sup>) Bond Formation through Cu-Catalyzed Cross-Coupling of<i>N</i>-Tosylhydrazones and Trialkylsilylethynes
作者:Fei Ye、Xiaoshen Ma、Qing Xiao、Huan Li、Yan Zhang、Jianbo Wang
DOI:10.1021/ja3004792
日期:2012.4.4
Copper-catalyzed cross-coupling of N-tosylhydrazones with trialkylsilylethynes leads to the formation of C(sp)-C(sp(3)) bonds. Cu carbene migratory insertion is proposed to play the key role in this transformation.
Transition‐Metal‐Free Cascade Enyne Rearrangement and Cyclopropanation of Allenylphosphine Oxides with
<i>N</i>
‐Tosylhydrazones Accessing Alkynylcyclopropane Derivatives
We disclose an concise synthesis of alkynylcyclopropane derivatives containing adjacent quaternary carbon centers via a transition-metal free cascade enyne rearrangement and cyclopropanation process. This methodology, started from a variety of allenylphosphine oxides and N-tosylhydrazones, features the advantage of transition-metal-free, operational simplicity, wide substrate scope and good functional
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。