Click Triazole Functionalized β-Cyclodextrin Supported Palladium:Efficient Catalyst for Suzuki Reaction in Neat Water

【作者】 栾玉新； 韩兴旺； 何成欢； 张国富； 丁成荣；

【Author】 Luan,Yuxin;Han,Xingwang;He,Chenghuan;Zhang,Guofu;Ding,Chengrong;College of Chemical Engineering and Materials Science,Zhejiang University of Technology;

【机构】 College of Chemical Engineering and Materials Science,Zhejiang University of Technology；

【摘要】 With increasing consideration about green chemistry,to develop efficient aqueous reactions has attracted much interest in recent years.Exploring water-soluble catalysts,such as sulfonic1 and quaternary ammonium salt,is one of the most practical approaches to improve aqueous reactions.However,many of them still need organic co-solvent to promote the solution of substrates or immobilize the catalytic species,which effects subsequent product isolation.Due to its special cavity structure and water solubility,β-cyclodextrin(β-CD),a commercial easily industrial product,has been broadly used in organic synthesis,especially in oxidation,reduction and hydrolysis reactions.Nevertheless,functionalizedβ-CD has not been fully exploited in Suzuki cross-coupling reaction,which is an excellent method to construct carbon-carbon bonds.Herein,we report a novel homogeneous palladium catalyst supported on triazole functionalizedβ-CD,which is synthesized via the copper-catalyzed click reaction2 between 2-ethynylpyridine and azide functionalizedβ-CD(Ln@β-CD).Characterization by 1HNMR and FT-IR spectra verified that the catalytic palladium species coordinated to the click-triazole,which acted also as a stable linker.The resulted catalyst showed excellent catalytic activity for Suzuki reactions in neat water,providing coupling products almost quantitatively under low Pd loadings(0.05 mol%).Besides iodobenzene,it’s also active for bromobenzene,tolerant of different functional groups.In addition,the catalyst was successfully reused for several recycles with consistent catalytic activity.This novel catalyst,taking advantage of bothβ-CD and dual-functional click triazole,might be widely applied to other aqueous reactions,such as hydrogenation,Henry reaction and etc.更多还原

【Abstract】 With increasing consideration about green chemistry,to develop efficient aqueous reactions has attracted much interest in recent years.Exploring water-soluble catalysts,such as sulfonic1 and quaternary ammonium salt,is one of the most practical approaches to improve aqueous reactions.However,many of them still need organic co-solvent to promote the solution of substrates or immobilize the catalytic species,which effects subsequent product isolation.Due to its special cavity structure and water solubility,β-cyclodextrin(β-CD),a commercial easily industrial product,has been broadly used in organic synthesis,especially in oxidation,reduction and hydrolysis reactions.Nevertheless,functionalized β-CD has not been fully exploited in Suzuki cross-coupling reaction,which is an excellent method to construct carbon-carbon bonds.Herein,we report a novel homogeneous palladium catalyst supported on triazole functionalized β-CD,which is synthesized via the copper-catalyzed click reaction2 between 2-ethynylpyridine and azide functionalized β-CD(Ln@β-CD).Characterization by 1HNMR and FT-IR spectra verified that the catalytic palladium species coordinated to the click-triazole,which acted also as a stable linker.The resulted catalyst showed excellent catalytic activity for Suzuki reactions in neat water,providing coupling products almost quantitatively under low Pd loadings(0.05 mol%).Besides iodobenzene,it’s also active for bromobenzene,tolerant of different functional groups.In addition,the catalyst was successfully reused for several recycles with consistent catalytic activity.This novel catalyst,taking advantage of both β-CD and dual-functional click triazole,might be widely applied to other aqueous reactions,such as hydrogenation,Henry reaction and etc.更多还原