N-Acyliminium Ion Rearrangements: Generalities and Application to the Synthesis of Pyrrolizidine Alkaloids

Article abstract of DOI:10.1021/jo00202a016

N-Acyliminium ions of the 2-aza-1,5-hexadienyl type frequently rearrange to isomeric ions by a process which is formally a 2-aza-Cope rearrangement.When gem-dimethyl substitution is present at C-4 of the initially formed N-acyliminium ion, the rearranged