N-Heterocyclic carbene (NHC)-catalyzed umpolung reactions [1] offer an elegant access to several important classes of compounds, such as benzoins [2] or g-butyrolactones.[3] In addition, Enders et al.[4] and Rovis et al.[5] have pioneered the development of a powerful NHC-catalyzed formation of highly functionalized chromanones by an intramolecular Stetter reaction.[6] Recently, we have reported the NHC-catalyzed hydroacylation of unactivated ...
