N-heterocyclic carbene-catalyzed homoenolate additions with N-aryl ketimines as electrophiles: efficient synthesis of spirocyclic γ-lactam oxindoles.

In pole position: A simple and efficient approach to spirocyclic γ-lactam oxindoles by the N-heterocyclic carbene catalyzed addition of homoenloate equivalents to N-aryl isatinimines has been developed (see scheme). The use of N-aryl isatinimines as electrophiles in the NHC-catalyzed umpolung reaction of α,β-unsaturated aldehydes is demonstrated for the first time.