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
A one-pot Barluenga coupling between N-tosylhydrazones and nitro-benzyl bromide, followed by deoxygenation of ortho-nitrostyrenes, and subsequent cyclization has been developed, providing a new way to synthesize various C2-arylindoles. This method exhibits a good substrate scope and functional group tolerance, and it allows an access to NH-free indoles, which can present a potential utility in medicinal