ON THE REACTION OF NITRILIUM SALTS WITH SECONDARY CARBOXAMIDES

Nitrilium salts 1, the first products of the Beckmann rearrangement of oximes, react with secondary amides 2, the final products of this rea rrangement, to afford mixtures of up to four different N-acylamidinium salts 3-6 (mechanism Scheme 4). The ratio 3/4/5/6 depends on the conf iguration of 2, the substituents of 1 and 2, the reaction temperature and the concentrations of the reactants. With tertiary amides nitriliu m salts give only one N-acylamidinium salt, the formation of which is also explained by the mechanism of Scheme 4. An X-ray structural analy sis in reported for the product obtained from 2-pyridone and N-isoprop ylbenzonitrilium hexachloroantimonate. First cyclic nitrilium salts (1 d, k, w) were prepared.