Remarkable effect of copper chloride on diiodination of zirconacyclopentadienes
摘要:
Treatment of zirconacyclopentadienes with two equiv of iodine in THF in the presence of 1.0 equiv of CuCl gave diiododienes in good to high yields without formation of monoiododienes. This is in sharp contrast to the case without CuCl which afforded monoiododienes as major products. For zirconacyclopentenes. CuCl was also effective but the use of ICl was more practical. When zirconacyclopentenes were treated with 2 equiv of ICl, only diiodination products were formed. Preparation of silacyclopentadienes or spiro compounds using the diidodienes was demonstrated. (C) 1997 Elsevier Science Ltd.
A reagent-dependent highly chemoselective halogenation reaction of zirconacyclopentenes
作者:Tamotsu Takahashi、Koichiro Aoyagi、Denis Y. Kondakov
DOI:10.1039/c39940000747
日期:——
Chemoselective monobromination reactions of 2,3-dialkylzirconacyclopentenes are highly reagent dependent; NBS or Br2 give alkenyl halide selectively, whereas CCl3Br or CBr4 give homoallylic halides with a high chemoselectivity.
Copper-catalyzed synthesis of five-membered heterocycles via double C–N bond formation: an efficient synthesis of pyrroles, dihydropyrroles, and carbazoles
作者:Ende Li、Xiaobing Xu、Hongfeng Li、Huimin Zhang、Xiaolei Xu、Xiyuan Yuan、Yanzhong Li
DOI:10.1016/j.tet.2009.08.075
日期:2009.10
An efficient copper-catalyzed double C-N bond forming reaction using diiodides and nitrogen-centered nucleophiles including amides and carbamates is reported. The reactions proceed to afford di- or tri-substituted N-acylpyrroles, dihydropyrroles, and carbazoles in good to excellent yields when different such as 1,4-diiodo-1,3-butadienes, 1,4-dihalobut-1-enes, and 2,2'-diiodobiphenyls were employed, respectively. It is crucial to use CuI as the catalyst with the assistance of proper base and diamine ligand. (C) 2009 Elsevier Ltd. All rights reserved.