Pyrylium-mediated transformations of natural products. Part 4. Reactions of water-soluble pyrylium salts with water and with amines

Abstract

Pyrylium cation equilibria and kinetics in aqueous solution have been measured and compared with existing data. Competing reactions of pyrylium cations with amines, water molecules, and hydroxide ions have been elucidated and rationalised. Conditions for maximising yields of pyridinium cations from pyrylium salts and amines in aqueous media have been deduced.