Efficient construction of biologically important functionalized polycyclic spiro-fused carbocyclicoxindoles via an asymmetric organocatalytic quadruple-cascade reaction?

RSC Advances Pub Date: 2017-01-12 DOI: 10.1039/C6RA24910H

Abstract

An efficient construction of highly functionalized polycyclic spiro-fused carbocyclicoxindoles has been developed via an asymmetric organocatalytic quadruple domino reaction of (E)-3-(2-hydroxybenzylidene)oxindole derivatives and two molecules of α,β-unsaturated aldehyde under quadruple iminium–enamine–iminium–enamine catalysis. The complex cascade products bearing a spiro quaternary center and five contiguous stereocenters were obtained in moderate to high yields (up to 90%) with good diastereoselectivities (up to 8?:?1) and excellent ee values (up to 99% ee). The structure and absolute configuration of the products were confirmed by NMR spectroscopy and single crystal X-ray analysis. In addition, the biological study showed that these compounds had moderate antitumor activities in the micromolar range.

Graphical abstract: Efficient construction of biologically important functionalized polycyclic spiro-fused carbocyclicoxindoles via an asymmetric organocatalytic quadruple-cascade reaction
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