Synthesis of enantioenriched spirocyclic oxindoles catalyzed by bifunctional thiourea

The spirocyclic oxindole scaffold, prevalent in natural products and bioactive compounds, holds paramount significance in organic chemistry. We report an efficient strategy for the construction of enantioenriched spirocyclic oxindoles bearing four consecutive stereogenic centers <i>via</i> a Michael-Mannich cascade reaction catalyzed by a bifunctional thiourea. The desired products were obtained in excellent yields (up to 99%) with high stereoselectivities (up to >20 : 1 d.r., >99% ee). A scaled-up reaction variant proceeded smoothly, highlighting the potential applicability of this method in the synthesis of bioactive compound libraries.