Cycloaddition-based Formal C–H Alkynylation of Isoindoles Leading to the Synthesis of Air-stable Fluorescent 1,3-Dialkynylisoindoles
摘要:
Reaction of N-alkylisoindoles with (bromoethynyl)triisopropylsilane afforded 1,3-bis(triisopropylsilylethynyl) isoindoles in high yields. The formal C-H alkynylation proceeds under transition-metal-free conditions through [4 + 2] cycloaddition of the pyrrole ring of isoindole with bromoalkyne followed by ring-opening of the product.
Side by side: Direct cis addition of bromoalkynes 1 to various alkynes 2 was found to proceed in the presence of a PdII catalyst to give difunctionalized enyneproducts3. The method is facile for the synthesis of bromo alkenynes. Furthermore, an unusual mechanism is proposed.
Strain versus flexibility: The palladium‐catalyzed reaction of haloalkynes with norbornene derivatives leads to 7‐alkynyl norbornane products (see scheme). Key to the success of this reaction is the formation of a “bridging” palladium species, which can rearrange to result in a C‐7 functionalization. The ring‐structure‐dependent [2+2] cycloaddition of haloalkynes with cyclooctene has been achieved in
Sulfilimines as Versatile Nitrene Transfer Reagents: Facile Access to Diverse Aza-Heterocycles
作者:Xianhai Tian、Lina Song、Matthias Rudolph、Frank Rominger、Thomas Oeser、A. Stephen K. Hashmi
DOI:10.1002/anie.201812002
日期:2019.3.11
We herein report the unprecedented synthesis of diverse biologically important aza‐heterocycles by employing sulfilimines as nitrenetransfer reagents. This class of sulfur‐based aza‐ylides had not been successfully used for gold nitrenetransfer before. This work contains an efficient generation of α‐imino gold carbenes by N−S cleavage of sulfilimines. These gold carbenes undergo C−H insertion, cyclopropanation
Au<sup>I</sup>-Catalyzed Hydroalkynylation of Haloalkynes
作者:Pedro D. García-Fernández、Javier Iglesias-Sigüenza、Paula S. Rivero-Jerez、Elena Díez、Enrique Gómez-Bengoa、Rosario Fernández、José M. Lassaletta
DOI:10.1021/jacs.0c07951
日期:2020.9.16
The AuI-catalyzed reaction between terminal alkynes and aromatic haloalkynes proceeds through divergent pathways depending on the nature of the catalyst counteranion. Thus, cationiccomplexes containing strongly basic NHC ligands and non-coordinating anions such as BArF4 catalyze the cis haloalkynylation of the terminal alkyne, whereas the introduction of a weakly basic triflate counteranion results
Facile and efficient synthesis of 1-haloalkynes via DBU-mediated reaction of terminal alkynes and N-haloimides under mild conditions
作者:Mengru Li、Yueju Li、Baozhong Zhao、Fushun Liang、Long-Yi Jin
DOI:10.1039/c4ra04736b
日期:——
Directly from terminal alkynes and with N-halosuccinimides (halo = Br and I) or N-cholorophthalimide as the halogen sources, DBU as the activator, 1-haloalkynes were prepared in good to excellent yields at room temperature.