Organocatalytic Asymmetric Michael/Cyclization Cascade Reactions of 3-Hydroxyoxindoles/3-Aminooxindoles with alpha,beta-Unsaturated Acyl Phosphonates for the Construction of Spirocyclic Oxindole-gamma-lactones/lactams

摘要

Enantioselective Michael/c-ydization cascade reactions of 3-hydroxyoxindoles/3-aminooxindoles with alpha,beta-unsaturated acyl phosphonates by using a cinchonine derived squaramide as the catalyst were developed. A broad range of spirocyclic oxindole-gamma-lactones/lactams could be obtained in moderate to excellent-Yields (up to 98%) with good to excellent diastereo- and enantioselectivities (up to >99:1 dr and 97% ee) under mild conditions. This work represents the first example - about the alpha,beta-unsaturated acyl phosphonates for the asymmetric construction of spirocyclic oxindoles.