Herein, we report that a series of novel palladium（II）-NHC complexes （NHC=N-heterocyclic carbene） were synthesized. The structures of all novel complexes were characterized by ^1H NMR, ^13C NMR, FT-IR spectroscopy...Herein, we report that a series of novel palladium（II）-NHC complexes （NHC=N-heterocyclic carbene） were synthesized. The structures of all novel complexes were characterized by ^1H NMR, ^13C NMR, FT-IR spectroscopy and elemental analysis techniques. These palladium（ll）-NHC complexes were tested as efficient catalysts in the direct C-H bond activation of benzoxazole and benzothiazole with aryl bromides in the presence of 1 mol% catalyst loading at 150 ℃ for 4 h. Under the given conditions, various aryl bromides were successfully applied as the arylating reagents to achieve the 2-arylbenzoxazoles and 2-arylbenzothiazoles in acceptable to high yields.展开更多
Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was foun...Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was found that 1,3 bis(2,4,6 trimethylphenyl) imidazolium chloride (IMesHCl) Pd 2(dba) 3 catalytic system has the highest activity to obtain phenyl malononitrile among the imidazolium salts. The substituted iodoarenes reacted with malononitrile anions by using the catalytic system to give cross coupling products in yields from 50% to 96%.展开更多
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 ...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.展开更多
Two new bis-imidazolinium salts (4a, 4b) have been synthesized as precursors of N-heterocyclic carbenes (NHCs) from the commercially available (R)-2,2′-dihydroxy-1,1′-binaphthalene. The two bis-imidazolinium salts w...Two new bis-imidazolinium salts (4a, 4b) have been synthesized as precursors of N-heterocyclic carbenes (NHCs) from the commercially available (R)-2,2′-dihydroxy-1,1′-binaphthalene. The two bis-imidazolinium salts were used as efficient precursor of NHC ancillary ligands in the palladium-catalyzed Heck reaction. Good to excellent yields and high stereoselectivities were obtained with ethyl acrylate, acrylonitrile, and acrylamide as starting materials. The structure of bis-imidazolinium salt 4b was further characterized by single crystal X-ray diffraction analysis.展开更多
Chiral C2-symmetric N-heterocyclic carbene （NHC） palladium diaquo complex 5b prepared from （S）-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to giv...Chiral C2-symmetric N-heterocyclic carbene （NHC） palladium diaquo complex 5b prepared from （S）-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.展开更多
文摘Herein, we report that a series of novel palladium（II）-NHC complexes （NHC=N-heterocyclic carbene） were synthesized. The structures of all novel complexes were characterized by ^1H NMR, ^13C NMR, FT-IR spectroscopy and elemental analysis techniques. These palladium（ll）-NHC complexes were tested as efficient catalysts in the direct C-H bond activation of benzoxazole and benzothiazole with aryl bromides in the presence of 1 mol% catalyst loading at 150 ℃ for 4 h. Under the given conditions, various aryl bromides were successfully applied as the arylating reagents to achieve the 2-arylbenzoxazoles and 2-arylbenzothiazoles in acceptable to high yields.
文摘Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was found that 1,3 bis(2,4,6 trimethylphenyl) imidazolium chloride (IMesHCl) Pd 2(dba) 3 catalytic system has the highest activity to obtain phenyl malononitrile among the imidazolium salts. The substituted iodoarenes reacted with malononitrile anions by using the catalytic system to give cross coupling products in yields from 50% to 96%.
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）.
文摘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support from the National Natural Science Foundation of China (20932004, 21072093)the National Basic Research Program of China (2011CB808600)+1 种基金the Program for New Century Excellent Talents in University (NCET-07-0425)the Doctoral Fund of Ministry of Education of China (20090091110017)
文摘Two new bis-imidazolinium salts (4a, 4b) have been synthesized as precursors of N-heterocyclic carbenes (NHCs) from the commercially available (R)-2,2′-dihydroxy-1,1′-binaphthalene. The two bis-imidazolinium salts were used as efficient precursor of NHC ancillary ligands in the palladium-catalyzed Heck reaction. Good to excellent yields and high stereoselectivities were obtained with ethyl acrylate, acrylonitrile, and acrylamide as starting materials. The structure of bis-imidazolinium salt 4b was further characterized by single crystal X-ray diffraction analysis.
文摘Chiral C2-symmetric N-heterocyclic carbene （NHC） palladium diaquo complex 5b prepared from （S）-BINAM was found to be a fairly effective catalyst for the enantioselective asymmetric fluorination of oxindoles to give the corresponding products in moderate enantioselectivities along with good to excellent yields.
基金supported by the National Natural Science Foundation of China (20925310)the National High Technology Research and Development Program of China (863 Program, 2009AA064201)+1 种基金the Science and Technology Commission of Shanghai Municipality (09XD1401500)the Shanghai Leading Academic Discipline Project (B409)~~
