“…N-Heterocyclic carbene (NHC)-mediated umpolung reactivity of aldehydes has enabled numerous highly significant reactions. − In recent years, NHC/transition metal cooperative catalysis has shown its robustness in creating new transformations and hence has received increasing attention. − Within this context, azolium homoenolate/enolate intermediates catalytically generated from NHC and carbonyls can be successfully captured by electrophiles activated by ruthenium, palladium, − iridium, ,, copper, ,− gold, and nickel complexes, leading to synthetically useful transformations and a greater understanding of reaction manifolds possibly occurring with NHC/TM cooperative catalysis. More recently, our group demonstrated that isatin-derived homoenolate equivalent I (Figure A) governs the geometry, facial selectivity, and regioselectivity of the oxindole moiety in a stereodivergent propargylic alkylation reaction .…”