Visible Light Mediated Generation of trans-Arylcyclohexenes and Their Utilization in the Synthesis of Cyclic Bridged...

While accessible via UV-irradiation of cis-cyclohexene, trans-cyclohexene has thus far been an investigation driven by curiosity, and due primarily to its short lifespan, has until recently not been employed for productive synthesis. Herein, we present straightforward conditions that provide access to a class of trans-arylcyclohexenes and demonstrate their utility in the formation of oxabicyclic ethers, which are otherwise inaccessible from the corresponding cis-cyclohexene. A key challenge to utilizing the incredible ca. 52 kcal/mol strain energy of trans-cyclohexene to drive synthesis was overcoming its short lifetime. Herein, we show that preorganization via hydrogen bonding between the substrate and the reaction partner prior to isomerization is a viable strategy to overcome the inherently short lifetime of trans-cyclohexene.