Reaction of ethoxyvinyl derivatives of pyrylium and pyridinium salts with primary and secondary amines

Abstract

The reaction of β-ethoxyvinylpyrylium salts with primary aromatic amines gives β-R-aminovinylpyrylium salts, the alkaline hydrolysis of which gives azomethines and, subsequently, pyranylideneacetaldehydes; reaction with methylamine gives N-methylpyridinium salts, which, under the influence of alkali, give pyridinylideneacetaldehydes, while reaction with secondary amines gives β-R,R′-dialkylaminovinylpyrylium salts or acetalacylals; reaction with acetate gives hydroxyvinylpyridines.