A DBU-catalyzed Michael-Pinner-isomerization cascade reaction of 3-hydroxyoxindoles with isatylidene malononitriles: access to highly functionalized bispirooxindoles containing a fully substituted dihydrofuran motif.

The first DBU-catalyzed Michael/Pinner/isomerization cascade reaction of 3-hydrooxindoles with isatylidene malononitriles was developed, and the corresponding highly functionalized bispirooxindoles containing a fully substituted dihydrofuran motif were obtained in up to 92% yields. This protocol also provides an efficient method for the synthesis of an α-cyano-γ-butyrolactone bispirooxindole. In addition, a one-pot three-component cascade reaction was conducted. Also, the asymmetric version of the cascade reaction was achieved.