Kinetics of Alkylation Reactions of Pyrrolizidine Alkaloid Pyrroles

Article abstract of DOI:10.1021/jo00226a027

Pyrrolizidine alkaloid pyrrolws react rapidly with 4-(p-nitrobenzyl)pyridine under pseudo-first order conditions.A biexpotential first-order rate law is observed.Relative reactivities are grewatly influenced by the nature of the leaving group at C7. 2,3-Dihydro-1H-pyrrolizin-1-ol and dehydrosupinidine under pseudo-first-order reaction conditions obey a simple first-order rate expression.Evidence for oligomerization of the pyrrolizidine pyrrole nucleus has been obtained under these reaction conditions, and it is proposed that a second color-forming reaction sequence of nucleophile with the oligomer C9s accounts for the biexpotential rate law.