176. Reaction of the 5-Azoniafulvene Ion with Enamines: A New Approach to Pyrrolizines

Article abstract of DOI:10.1002/hlca.19910740824

The synthesis of N,N-dimethyl-N-<(pyrrol-1-yl)methyl>anilinium chloride (14) and of the corresponding p-toluidinium salt 15 is described.These salts, when dissolved in polar solvents, are shown to be in equilibrium with 1-(chloromethyl)pyrrole (17) and thereby potentially with the 5-azoniafulvene ion (2).Consequently, they react under very mild conditions (MeCN, 60 deg C) with enamines to give pyrrolizine derivatives in acceptable yield (40-50percent).The process is rationalized in terms of an initial Mannich-type reaction which is immediately followed by a cyclization.