Synthesis and diversification of chiral spirooxindols via organocatalytic cascade reactions

Herein, the synthesis of chiral spirooxindols through different amino catalytic activation modes is described. Several dienophiles were obtained from the Knoevenagel reaction of isatin and activated methylene derivatives containing electron withdrawing groups, such as ethyl cyanoacetate. A spirooxindol derivative was obtained from the oxa-Michael-Michael reaction between one of the synthesized dienophiles and 2-hydroxycinnamaldehyde. Currently, new methodologies that allow access to spirooxindol scaffolds are being explored, mainly though Diels-Alder reactions between 2-methylenindolin-2-ones and aldehydes with trienamine activation mode. The following cascade reactions will be explored in the future to obtain the proposed polycyclic spirooxindol derivatives.