Harnessing NHC/Base-Catalyzed Regiodivergent Oxidative Cyclization for Versatile Aminolactone Synthesis

A regiodivergent oxidative cyclization of ynamide-tethered benzaldehydes has been achieved using an organocatalytic approach based on NHC/base. The method enables the efficient synthesis of aminolactones with high regioselectivity, including the formation of 5-exo products through umpolung β-addition of ynamides. The reaction involves NHC-catalyzed aerobic oxidation of the benzaldehyde moiety followed by cyclization toward the ynamide. Computational and experimental studies have shed light on the significance of proton dissociation from the in situ generated carboxylic acid in determining the regioselectivity of the reaction. The synthetic versatility and value of aminolactones obtained from this method are also highlighted.