Enantioselective Synthesis of Spirooxindole Derivatives through Lewis Acid-Catalyzed Michael Addition/Cyclization Cascade

A Mg(OTf)2-catalyzed asymmetric Michael addition/cyclization cascade reaction between 3-isothiocyanato oxindoles and 2-arylidene-1,3-indanediones has been developed. This transformation provides an efficient and concise approach to biologically important bispiro[indanedione-oxindole-pyrrolidinyl]s under mild conditions in good to excellent yields (70-99% yields) with moderate to good stereoselectivities (up to 99% ee and >95:5 d.r.). Notably, biological investigation reveals that one of the synthesized bispiro[indanedione-oxindole-pyrrolidinyl]s exhibits promising cytotoxicity against NCI-H460 human lung cancer and SW-620 human colon cancer cells.