Organocatalytic oxa/aza-Michael–Michael Cascade Strategy for the Construction of Spiro [Chroman/Tetrahydroquinoline-3,3′-oxindole] Scaffolds

A new useful and effective chiral amine-catalyzed oxa- and aza-Michael–Michael cascade methodology for the construction of enantiomerically enriched indolinones spiro-fused with chromans or tetrahydroquinolines is reported. By employing suitable organocatalysts depending on the different Michael donors (Ar-OH/Ar-NHR), the processes offered excellent stereocontrol (dr >20:1, >99% ee) under mild conditions.