摘要
Novel acyclic Pd（II）-N-heterocyclic carbene （NHC） metallacrown ethers 5a, 5b have been synthesized. Reaction of the imidazolium salts hearing a long polyether chain with Ag2O afforded Ag-NHC complexes, which then reacted as carbene transfer agent with PdCl2（MeCN）2 to give the desired acyelic Pd（Ⅱ）-NHC metallacrown ether complexes 5a and 5b. The 1H NMR and 13C NMR spectra show fia and fib exist as mixtures ofcis and trans isomers in solution. The trans isomer of 5a was characterized by X-ray diffraction, which clearly demonstrated two pseudo-crown ether cavities in trans-5a. Pd（Ⅱ）-NHC complexes 5a and 5b have been shown to be highly effective in the Suzuki-Miyaura reactions of a variety of aryl bromides in neat water without the need of inert gas protection.
Novel acyclic Pd（II）-N-heterocyclic carbene （NHC） metallacrown ethers 5a, 5b have been synthesized. Reaction of the imidazolium salts hearing a long polyether chain with Ag2O afforded Ag-NHC complexes, which then reacted as carbene transfer agent with PdCl2（MeCN）2 to give the desired acyelic Pd（Ⅱ）-NHC metallacrown ether complexes 5a and 5b. The 1H NMR and 13C NMR spectra show fia and fib exist as mixtures ofcis and trans isomers in solution. The trans isomer of 5a was characterized by X-ray diffraction, which clearly demonstrated two pseudo-crown ether cavities in trans-5a. Pd（Ⅱ）-NHC complexes 5a and 5b have been shown to be highly effective in the Suzuki-Miyaura reactions of a variety of aryl bromides in neat water without the need of inert gas protection.
基金
Supporting information for this article is available on the WWW under http：//dx.doi.org/10.1002/cjoc.201100596 or from the author.Acknowledgement This work was supported by the Natural Science Foundation of China （Nos. 21021001, 21072134） and Program for Changjiang Scholars and Innovative Research Team in University （No. IRT0846）.
