Highly Asymmetric NHC-Catalyzecl Hydroacylation of Unactivated Alkenes

摘要

N-Heterocyclic carbene (NHC)-catalyzed umpolung reactions offer an elegant access to several important classes of compounds, such as benzoins or γ-butyrolactones. In addition, Enders et al. and Rovis et al. have pioneered the development of a powerful NHC-catalyzed formation of highly functionalized chromanones by an intramolecular Stetter reaction. Recently, we have reported the NHC-catalyzed hydroacylation of unactivated olefins, a reaction previously only possible with transition-metal catalysts. This intramolecular reaction was also found to be a versatile method for the synthesis of numerous racemic chromanones. However, the mechanism remained unclear.