Metal‐Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde‐Derived Silyl Enol Ethers
作者:Avijit Roy、Martin Oestreich
DOI:10.1002/chem.202100877
日期:2021.6.4
catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enolethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using
Chiral spiro phosphoric acid-catalysed enantioselective reaction of ketenes with N–H pyrroles
作者:Qian-Yi Wang、Teng-Fei Liu、Li-Feng Chu、Yun Yao、Chong-Dao Lu
DOI:10.1039/d1cc05307h
日期:——
In the presence of a chiral spiro phosphoric acid catalyst, the asymmetric reaction of disubstituted ketenes with N–H pyrroles occurred to afford enantioenriched C-acylated pyrroles bearing α-stereogenic carbon centres. The described reaction constitutes a rare example of a catalytic asymmetric reaction of ketenes with carbon-based nucleophiles.
Oxindole synthesis <i>via</i> polar–radical crossover of ketene-derived amide enolates in a formal [3 + 2] cycloaddition
作者:Niklas Radhoff、Armido Studer
DOI:10.1039/d1sc07134c
日期:——
and transition-metal free method for the preparation of valuable and sterically hindered 3,3-disubstituted oxindoles via polar–radical crossover of ketene derived amide enolates. Various easily accessible N-alkyl and N-arylanilines are added to disubstituted ketenes and the resulting amide enolates undergo upon single electron transfer oxidation a homolytic aromatic substitution (HAS) to provide 3,3-disubstituted
difluoroenoxysilanes is disclosed for the first time, which enabled the direct construction of versatile gem-difluoroalkenes through an unprecedented highly efficient addition reaction with ketenes. A series of valuable gem-difluoroenol esters were achieved in good to excellent yields. The synthetic versatility of this protocol is further demonstrated by the gram-scale synthesis and good functional group tolerance
Lewis Acid Catalyzed Formal (3+2)‐Cycloaddition of Bicyclo[1.1.0]butanes with Ketenes
作者:Niklas Radhoff、Constantin G. Daniliuc、Armido Studer
DOI:10.1002/anie.202304771
日期:2023.8.21
efficient and transition-metal-free method for the preparation of valuable bicyclo[2.1.1]hexanes by Lewisacid catalyzed formal (3+2)-cycloaddition of readily available bicyclo[1.1.0]butanes and ketenes is presented. Excellent tolerance towards functional groups and versatile substitution patterns in the 3-position of the bicyclo[2.1.1]hexane core are demonstrated.