A combined theoretical and experimental investigation into the highly stereoselective migration of spiroindolenines.

This paper describes a combined theoretical and experimental investigation into the acid-catalyzed migration of spiroindolenines to the corresponding fused cyclic products. It is suggested that the "three-center-two-electron"-type transition state is the crucial reason accounting for the highly stereoselective phenomenon. Further studies demonstrated that the electronic property of the migratory group as well as the ring size may have a major influence on the reaction profile of the migration process. Some predictions based on the computational results were supported by additional experiments.