The methylation of alcohols is of great importance since a broad number of bioactive and pharmaceutical alcohols contain methyl groups.Here,a highly efficientβ-methylation of primary and secondary alcohols with metha...The methylation of alcohols is of great importance since a broad number of bioactive and pharmaceutical alcohols contain methyl groups.Here,a highly efficientβ-methylation of primary and secondary alcohols with methanol has been achieved by using bis-N-heterocyclic carbene iridium(bis-NHC-Ir)complexes.Broad substrate scope and up to quantitative yields were achieved at low catalyst loadings with only hydrogen and water as by-products.The protocol was readily extended to theβ-alkylation of alcohols with several primary alcohols.Control experiments,along with DFT calculations and crystallographic studies,revealed that the ligand effect is critical to their excellent catalytic performance,shedding light on more challenging Guerbet reactions with simple alcohols.展开更多
Summary of main observation and conclusion A metal-free reaction of nitrosoarenes,aryldiazonium tetrafluoroborates,and sulfur dioxide under mild conditions is developed,giving rise to sulfonamides in moderate to good ...Summary of main observation and conclusion A metal-free reaction of nitrosoarenes,aryldiazonium tetrafluoroborates,and sulfur dioxide under mild conditions is developed,giving rise to sulfonamides in moderate to good yields.This transformation proceeds eficiently at room temperature in the presence of cyclohexa-1,4-diene with a broad reaction scope.Good functional group compatibility is observed,including cyano,halo,and ester.A plausi-ble mechanism involving a radical process with the insertion of sulfur dioxide is proposed,and cyclohexa-1,4-diene serves as the reductant during the transformation.展开更多
基金This work was supported by the National Key R&D Program of China(2016YFA0202902)the National Natural Science Foundation of China(21871059,21861132002)and the Department of Chemistry at Fudan University.
文摘The methylation of alcohols is of great importance since a broad number of bioactive and pharmaceutical alcohols contain methyl groups.Here,a highly efficientβ-methylation of primary and secondary alcohols with methanol has been achieved by using bis-N-heterocyclic carbene iridium(bis-NHC-Ir)complexes.Broad substrate scope and up to quantitative yields were achieved at low catalyst loadings with only hydrogen and water as by-products.The protocol was readily extended to theβ-alkylation of alcohols with several primary alcohols.Control experiments,along with DFT calculations and crystallographic studies,revealed that the ligand effect is critical to their excellent catalytic performance,shedding light on more challenging Guerbet reactions with simple alcohols.
基金Financial support from the National Natural Science Foundation of China(Nos.21871053,21532001 and 21762018)the Natural Science Foundation of Jiangxi Province(No.20192BCBL23009)。
文摘Summary of main observation and conclusion A metal-free reaction of nitrosoarenes,aryldiazonium tetrafluoroborates,and sulfur dioxide under mild conditions is developed,giving rise to sulfonamides in moderate to good yields.This transformation proceeds eficiently at room temperature in the presence of cyclohexa-1,4-diene with a broad reaction scope.Good functional group compatibility is observed,including cyano,halo,and ester.A plausi-ble mechanism involving a radical process with the insertion of sulfur dioxide is proposed,and cyclohexa-1,4-diene serves as the reductant during the transformation.
