A series of salicylaldimine ligands were designed to promote the copper-catalyzed Ullmann cross- coupling reaction. After a screening process, 2-（（2-isopropylphenylimino）methyl）phenol was found to serve as a good ...A series of salicylaldimine ligands were designed to promote the copper-catalyzed Ullmann cross- coupling reaction. After a screening process, 2-（（2-isopropylphenylimino）methyl）phenol was found to serve as a good supporting ligand for this reaction. Employing this Schiff-base ligand as a new supporting ligand, the copper-catalyzed coupling reactions of aryl bromides and aryl iodides with various phenols successfully proceeded in good yields under mild conditions. Various diaryl ethers were obtained with excellent yields in dioxane in the presence of K3P04 and a catalytic amount of copper（I） salt.展开更多
Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers t...Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.展开更多
基金the National Natural Science Foundation of ChinaKey Laboratory of Organic Synthesis of Jiangsu Province for the financial support(Nos.21201147,21302063,KJS1112)
文摘A series of salicylaldimine ligands were designed to promote the copper-catalyzed Ullmann cross- coupling reaction. After a screening process, 2-（（2-isopropylphenylimino）methyl）phenol was found to serve as a good supporting ligand for this reaction. Employing this Schiff-base ligand as a new supporting ligand, the copper-catalyzed coupling reactions of aryl bromides and aryl iodides with various phenols successfully proceeded in good yields under mild conditions. Various diaryl ethers were obtained with excellent yields in dioxane in the presence of K3P04 and a catalytic amount of copper（I） salt.
基金financially supported by the National Natural Science Foundation of China(Nos.21801236 and U1862206)。
文摘Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.
