Radical Cation Diels-Alder Reaction Research Articles

Radical cation Diels-Alder reaction of indoles and exocyclic dienes

A convergent synthesis of [b]-annelated tetrahydrocarbazoles through a radical cation Diels-Alder reaction is described. The reaction is induced by photo electron transfer (PET). The previously predicted stepwise mechanism of this reaction is proved by stereochemical analysis of the products.

Radical cations of cyclopentadiene dimers—facets of an intriguing energy surface

The radical cations of various cyclopentadiene dimers can be generated by photoinduced electron transfer to strong electron acceptors. Nuclear spin polarization effects observed during these reactions provide insight into the radical cation structures. Three of the systems studied, endo-[4 + 2]-( 1), anti-[2+2]-( 2), and exo-(4+2]-dicyclopentadiene ( 5) give rise to unusual singly linked, delocalized radical cations, whereas the anti-[4 + 4]-dimer ( 3) and 1,3-bishomocubane ( 4) give rise to more conventional radical cations. The reactions of spiroheptadiene ( 9) and di(spiroheptadiene) ( 10) provide evidence for two different dimer radical cations, a doubly linked (D) and a singly linked (S) species. This finding supports a stepwise mechanism for the radical cation Diels-Alder reaction of 9.