DEVELOPMENT OF AN INTRAMOLECULAR GASSMAN'S [2+2] CYCLOADDITION

The development of an intramolecular variant of Gassman's cationic [2 + 2] cycloaddition is described herein. Mechanistic aspects of the stepwise nature of this cycloaddition process between vinyl acetals and unactivated olefins have been studied. We have also explored the scope of this reaction with regard to various oxygen-, nitrogen-, and carbon-tethered acetals to provide access to a diverse array of bicyclic scaffolds. Additionally, we have identified vinyl hemiaminals as having favorable reactivity for cationic [2 + 2] cycloaddition.