Umpolung Strategy for the Synthesis of Chiral Dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles

Based on a novel umpolung strategy, an efficient and highly enantioselective cascade aldol/cyclization/tautomerization of the 2-(2-oxoindolin-3-yl)­malononitrile to active carbonyl compounds with excellent diastereo- and enantioselectivity has been developed. Also, various enantio-enriched multifunctional dispiro­[2-amino-4,5-dihydrofuran-3-carbonitrile]­bisoxindoles with adjacent spiro-stereocenters were conveniently obtained by this novel methodology. Also, the dispiro­[2-amino-4,5-dihydrofuran-3-carbonitrile]­bisoxindoles were easily transformed into structurally complex molecules without any effect on the diastereo- and enantioselectivity.