Synthetic applications of N-N linked heterocycles. Part 15. A facile synthesis of 4-pyridyl(aryl)amines via the reaction between 4-chloro-1-pyridiniopyridinium salts and aryl amines

Abstract

4-Chloro-1-pyridiniopyridinium salts (7) and (8) react with primary and secondary arylamines to give high yields of isolable 4-aryliminium salts (9) and (10). These are readily fragmented into 4-pyridyl(aryl)-amines (11) and (12) in excellent yields on treatment with sodium cyanide or sodium salts of sulphinic acids. The method fails with the more basic aliphatic amines, since these apparently attack the 2-position of the chloropyridinium ring giving products resulting from ring-opening. Mechanisms of the reactions are discussed.