Strain Release [2p+2s]-Cycloadditions for the Synthesis of [2.1.1]-Bicyclohexanes Initiated by Energy Transfer

Saturated bicycles are becoming ever more important in the design and development of new pharmaceuticals. In this manuscript, a new strategy for the synthesis of [2.1.1]-bicyclohexanes is described. These bicycles are significant as they have defined exit vectors, yet many substitution patterns are underexplored as building blocks. The process involves sensitization of a [1.1.0]-bicyclobutane followed by cycloaddition with an alkene. The scope and mechanistic details of the methods are discussed.