Stereoselective N-heterocyclic-carbene-catalyzed spiroannulation as an access towards spirobenzofuranone-fused cyclohexenones

Heterocyclic spirocyclic compounds as structurally unique compounds are present in many natural or bioactive compounds. Not surprisingly, developing novel methodologies that enable stereocontrol access toward spirocyclic compounds represents an important goal in modern synthetic chemistry. The main interest is oriented toward developing methods for accessing spirooxindoles. On the other hand, the development of their oxygen-containing cousins is still overlooked. Here, we report a simple organocatalytic spiroannulation method, which provides access to spirocyclic benzofuran-2-ones. The utility of the protocol was underscored by gram-scale reaction and follow-up transformations.