Radical Cation Diels-Alder Reactions of Non-Conjugated Alkenes as Dienophiles by Electrocatalysis

Radical cation Diels-Alder reactions provide a powerful method for the construction of six-membered ring systems between both electron-rich dienes and dienophiles. However, the most recent examples of this class have been limited to beta-methylstyrenes as dienophiles; the use of non-conjugated alkenes remains challenging. The present study describes the serendipitous development of novel radical cation Diels-Alder reactions by electrocatalysis that use non-conjugated alkenes as dienophiles. The key to successful transformation involves highly substituted cyclohexenyl radical cations that are stable enough to be reduced by intermolecular single electron transfer.