Enantioselective Construction of Bispirooxindoles via Squaramide-Catalysed Cascade Michael/Cyclization Reaction

A series of readily available 2-(2-oxoindolin-3-yl)malononitriles bearing multiple active sites were first used in asymmetric catalytic synthesis, which have been successfully applied to develop a bifunctional squaramide-catalyzed cascade Michael/cyclization reaction strategy. Various cyclopentene-bispirooxindoles with three continuous stereocenters, two of which are quaternary spiro-stereocenters, were constructed in good yields with excellent stereoselectivities (up to >20:1 dr, >99% ee). (Figure presented.).