Nucleophilic Displacements of N-Aryl and Heteroaryl Groups. Part 3. Pyrylium-mediated Synthesis of Unsymmetrical Diarylamines from Anilines

Article abstract of DOI:10.1039/P19830002611

2-Ethoxycarbonyl-4,6-diphenylpyrylium salts (1) reacted with various ring-substituted anilines to give the corresponding pyridinium salts (2) (average yield 90percent); these were hydrolysed to the pyridinium betaines (3) (75percent) and treated with thionyl chloride followed by an aniline to give the amides (4) (70percent).Refluxing in toluene with sodium hydride for 12 h transfers intramolecularly the 1-aryl group of the pyridinium salt(4) to the nitrogen of the amide.Aqueous work-up cleaves (6) and the diarylamine is purified by sublimation (60percent) (overall yield ca. 30percent).