Polar effects in free-radical reactions. Carbamoylation and α-N-amidoalkylation of heteroaromatic bases by amides and hydroxylamine-O-sulfonic acid

NH3+·, formed in the decompn. of H3N+OSO3- by Fe2+, generates carbamoyl and α-N-amidoalkyl radicals by H abstraction from formamide, alkylformamides, and N-alkylacetamides. Both carbamoyl and α-N-amidoalkyl radicals have a clear-cut nucleophilic character and selectively attack protonated heteroarom. bases, e.g., 4-methylquinoline or quinoxaline, in the α-position or are oxidized by Fe(III) salts. Redox chain mechanisms are involved. The importance of the polar effects in the H abstraction, arom. substitution, and oxidn. by Fe(III) salt is discussed