Assembly of Spirooxindole Derivatives Containing Four Consecutive Stereocenters via Organocatalytic Michael–Henry Cascade Reactions
作者:Klaus Albertshofer、Bin Tan、Carlos F. Barbas
DOI:10.1021/ol300441z
日期:2012.4.6
A novel organocatalytic strategy for the synthesis of highly substituted spirocyclopentaneoxindoles was developed employing simple nitrostyrenes and 3-substituted oxindoles as starting materials. Michael–Henry cascadereactions, enabled through cinchona alkaloid organocatalysis, provided products in high yield and excellent enantioselectivity in a single step.
Construction of bispirooxindoles containing three quaternary stereocentres in a cascade using a single multifunctional organocatalyst
作者:Bin Tan、Nuno R. Candeias、Carlos F. Barbas
DOI:10.1038/nchem.1039
日期:2011.6
Single-step constructions of molecules with multiple quaternary carbon stereocentres are rare. The spirooxindole structural motif is common to a range of bioactive compounds; however, asymmetric synthesis of this motif is complicated due to the presence of multiple chiral centres. The development of organocatalytic cascade reactions has proven to be valuable for the construction of several chiral centres
Diastereoselective tandem oxidation/Michael/aldol reaction: unprecedented formation of dispirocyclopentanebisoxindoles and dispiro[acenaphthylene-1,1′-cyclopentane-3′,1′′-acenaphthylene]-2,2′′diones
An unprecedented tandem oxidation/Michael/aldolreaction is reported. The diastereoselective formation of only a single isomer of dispirocyclopentanebisoxindole and dispiro[acenaphthylene-1,1′-cyclopentane-3′,1′′-acenaphthylene]-2,2′′dione is presented. The reaction generates two new C–C bonds and two all-carbon quaternary chiral stereocenters in a single step.