A photocatalytic tandem cyclization of o-alkenylbenzaldehydes using pyridinium salts as the amination reagent is described.A variety of valuable seven-membered nitrogenous heterocyclic skeletons are prepared in modest...A photocatalytic tandem cyclization of o-alkenylbenzaldehydes using pyridinium salts as the amination reagent is described.A variety of valuable seven-membered nitrogenous heterocyclic skeletons are prepared in modest to excellent yields in concise one-step.This transformation features mild reaction conditions and exceptional functional group tolerance.In addition,combining control experiments and density functional theory(DFT)calculations on the mechanism can explain the reaction selectivity.展开更多
The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals a...The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals and N-nucleophiles to conduct 1,2-difunctional amination/azolization of alkenes.In contrast,2,1-difunctional amination/azolization of alkenes by using nitrogen-centered radicals(NCRs) and nucleophiles still remains rarely underexplored.It is possibly due to the highly active electron properties of NCRs and the relatively poor nucleophilicity of aromatic NCRs to be trapped by arylalkenes.Herein,we demonstrate an unprecedented 2,1-hydroxazolization reactions of arylalkenes through electrochemically enabled addition of NCRs from azoles and nucleophiles(NuH) in high yields and with high regioselectivity.This conversion is characterized by the fact that neither metal catalysts nor external chemical oxidants are required.This electrochemical oxidation synthesis method can also be applied for a broad range of NuH including pyridine hydrofluoride,ammonia,water,alcohols,and acids which enables the formation of C-N and C-X(X=F/N/O) bonds in one-pot fashion to furnish efficient fluoroamination,diamination and oxoamination of alkenes.展开更多
Catalytic amination of alkenes is one of the most attractive reactions for the construction of complex heterocycles with nitrogen centers. Herein, we present that synergistic photoredox and cobaloxime catalysis allows...Catalytic amination of alkenes is one of the most attractive reactions for the construction of complex heterocycles with nitrogen centers. Herein, we present that synergistic photoredox and cobaloxime catalysis allows for highly efficient and mild dehydrogenative reactions between various NH nucleophiles and di-, tri-, and tetrasubstituted alkenes in the absence of external oxidants, thus enabling access to an array of N-heterocycles. Notably, both Z-and E-alkene-containing N-heterocycles are accessible. Mechanistic studies indicated that the Z-cinnamyl derivatives could be generated by photocatalytic E to Z alkene isomerization through an energy transfer process. Moreover, we find that sluggish energy transfer could inhibit the E to Z alkene isomerization process, thus offering the cinnamyl derivatives with E-selectivity. Our results highlight the benefits of the reactions using dual photoredox and cobaloxime catalysis to lead to diverse N-heterocycles.展开更多
基金the National Natural Science Foundation of China(21632003,21871116)the Key Program of Gansu Province(17ZD2GC011)the‘‘111’’Program from the MOE of China。
文摘A photocatalytic tandem cyclization of o-alkenylbenzaldehydes using pyridinium salts as the amination reagent is described.A variety of valuable seven-membered nitrogenous heterocyclic skeletons are prepared in modest to excellent yields in concise one-step.This transformation features mild reaction conditions and exceptional functional group tolerance.In addition,combining control experiments and density functional theory(DFT)calculations on the mechanism can explain the reaction selectivity.
基金the National Science Foundation of China(No.22071058)the Fundamental Research Funds for the Central Universities for financial support。
文摘The direct difunctionalization of alkenes serves as one of the most straightforward strategies toward complex nitrogen-containing compounds.The existing approach is extensively promoted by using C/Xcentered radicals and N-nucleophiles to conduct 1,2-difunctional amination/azolization of alkenes.In contrast,2,1-difunctional amination/azolization of alkenes by using nitrogen-centered radicals(NCRs) and nucleophiles still remains rarely underexplored.It is possibly due to the highly active electron properties of NCRs and the relatively poor nucleophilicity of aromatic NCRs to be trapped by arylalkenes.Herein,we demonstrate an unprecedented 2,1-hydroxazolization reactions of arylalkenes through electrochemically enabled addition of NCRs from azoles and nucleophiles(NuH) in high yields and with high regioselectivity.This conversion is characterized by the fact that neither metal catalysts nor external chemical oxidants are required.This electrochemical oxidation synthesis method can also be applied for a broad range of NuH including pyridine hydrofluoride,ammonia,water,alcohols,and acids which enables the formation of C-N and C-X(X=F/N/O) bonds in one-pot fashion to furnish efficient fluoroamination,diamination and oxoamination of alkenes.
基金supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (18KJA350001)the Priority Academic Program Development of the Jiangsu Higher Education Institutes (PAPD)。
文摘Catalytic amination of alkenes is one of the most attractive reactions for the construction of complex heterocycles with nitrogen centers. Herein, we present that synergistic photoredox and cobaloxime catalysis allows for highly efficient and mild dehydrogenative reactions between various NH nucleophiles and di-, tri-, and tetrasubstituted alkenes in the absence of external oxidants, thus enabling access to an array of N-heterocycles. Notably, both Z-and E-alkene-containing N-heterocycles are accessible. Mechanistic studies indicated that the Z-cinnamyl derivatives could be generated by photocatalytic E to Z alkene isomerization through an energy transfer process. Moreover, we find that sluggish energy transfer could inhibit the E to Z alkene isomerization process, thus offering the cinnamyl derivatives with E-selectivity. Our results highlight the benefits of the reactions using dual photoredox and cobaloxime catalysis to lead to diverse N-heterocycles.
