Cycloaddition of Enamine and Iminium Ion Intermediates Formed in the Reaction of N-Arylpyrrolidines with T-HYDRO

Abstract

The reaction of <i>N</i>-arylpyrrolidine derivatives with 70% aqueous <i>tert</i>-butyl hydroperoxide (T-HYDRO) in the presence of NaOAc·3H₂O gives tetracyclic amines in 59–78% yields via cycloaddition of the corresponding iminium ion and enamine intermediates formed in situ in cyclohexane solvent. The iminium ion intermediate reacts with <i>t</i>-BuOK in methanol to give the corresponding cyclic amides in 85–88% yields or undergoes alkylation to give the corresponding nitromethyl product in 74–79% yields using <i>t</i>-BuOK and nitromethane in methanol.