A copper-catalyzed cyanation/diarylmethylation of formamides has been developed for the synthesis ofα-cyano functionalized tetra-substituted olefins by utilizing para-quinone methides(p-QMs)and trimethylcyanosilane a...A copper-catalyzed cyanation/diarylmethylation of formamides has been developed for the synthesis ofα-cyano functionalized tetra-substituted olefins by utilizing para-quinone methides(p-QMs)and trimethylcyanosilane as functionalization sources.Various kinds of p-QMs and formamides are well tolerated,delivering the desired products with 72%—94%yields,demonstrating broad functional group tolerance.Notably,the reaction does not require noble metals and proceeds regioselectively under mild conditions.Based on step-by-step control experiments,Hammett studies and DFT calculation,a plausible mechanism is proposed.展开更多
In this study,a series of double-layered stericα-diimine nickel and palladium complexes containing bulky diarylmethyl moieties with remote 4-cycloalkyl and-phenyl substituents were designed and synthesized.The as-syn...In this study,a series of double-layered stericα-diimine nickel and palladium complexes containing bulky diarylmethyl moieties with remote 4-cycloalkyl and-phenyl substituents were designed and synthesized.The as-synthesized nickel complexes showed high activities(ca.10^(6) g mol^(-1) h^(-1))and superior thermal stability,giving access to moderately branched polyethylenes with high molecular weights and narrow molecular weight distributions at high temperatures.With the rigid-flexible double-layered steric nickel catalysts,high temperature living polymerizations at 80°C were achieved.The polyethylene materials yielded by these nickel catalysts at 80℃ exhibited outstanding tensile mechanical and elastic recovery properties(SR up to 86%).Correspondingly,the palladium complexes displayed moderate activities in ethylene polymerization,producing moderately branched polyethylenes with high molecular weights.The polyethylene materials yielded by palladium complexes at 60℃ exhibited good tensile mechanical properties and moderate elastic recovery values.In addition,these palladium complexes could also promote ethylene-polar monomer copolymerization,albeit with modest activity,yielding polar functionalized polyethylenes with moderate levels of branching densities,molecular weights,and incorporation ratios.Overall,the rigid-flexible double-layered steric nickel and palladium complexes with remote cyclohexyl substituents were found to have significantly higher activities than their rigid-rigid double-layered steric or monolayered dibenzhydryl counterparts in alkane solvents.展开更多
基金supported by the Natural Science Foundation of Hunan Province(2023JJ30274,2023JJ30275)Scientific Research Fund of Hunan Provincial Education Department(23A0497,23B0634)+1 种基金National Natural Science Foundation of China(22308116)Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515110118).
文摘A copper-catalyzed cyanation/diarylmethylation of formamides has been developed for the synthesis ofα-cyano functionalized tetra-substituted olefins by utilizing para-quinone methides(p-QMs)and trimethylcyanosilane as functionalization sources.Various kinds of p-QMs and formamides are well tolerated,delivering the desired products with 72%—94%yields,demonstrating broad functional group tolerance.Notably,the reaction does not require noble metals and proceeds regioselectively under mild conditions.Based on step-by-step control experiments,Hammett studies and DFT calculation,a plausible mechanism is proposed.
基金supported by the Natural Science Foundation of Anhui Province(2108085Y06)the Anhui Provincial Key Laboratory Open Project Foundation(LCECSC-01)the Natural Science Research Projects of Universities in Anhui Province(KJ2021A0066).
文摘In this study,a series of double-layered stericα-diimine nickel and palladium complexes containing bulky diarylmethyl moieties with remote 4-cycloalkyl and-phenyl substituents were designed and synthesized.The as-synthesized nickel complexes showed high activities(ca.10^(6) g mol^(-1) h^(-1))and superior thermal stability,giving access to moderately branched polyethylenes with high molecular weights and narrow molecular weight distributions at high temperatures.With the rigid-flexible double-layered steric nickel catalysts,high temperature living polymerizations at 80°C were achieved.The polyethylene materials yielded by these nickel catalysts at 80℃ exhibited outstanding tensile mechanical and elastic recovery properties(SR up to 86%).Correspondingly,the palladium complexes displayed moderate activities in ethylene polymerization,producing moderately branched polyethylenes with high molecular weights.The polyethylene materials yielded by palladium complexes at 60℃ exhibited good tensile mechanical properties and moderate elastic recovery values.In addition,these palladium complexes could also promote ethylene-polar monomer copolymerization,albeit with modest activity,yielding polar functionalized polyethylenes with moderate levels of branching densities,molecular weights,and incorporation ratios.Overall,the rigid-flexible double-layered steric nickel and palladium complexes with remote cyclohexyl substituents were found to have significantly higher activities than their rigid-rigid double-layered steric or monolayered dibenzhydryl counterparts in alkane solvents.
