Polar Effects in Free-Radical Reactions. Carbamoylation and α-N-Amidoalkylation of Heteroaromatic Bases by Amides and Hydroxylamine-O-sulfonic Acid.

Article abstract of DOI:10.1021/jo00192a022

The decomposition by Fe(II) salt of hydroxylamine-O-sulfonic acid (HSA) in the presence of formamide, alkylformamides, and N-alkylacetamides provides the amino radical cation *⁺NH3, which by hydrogen abstraction generates carbamoyl (*CON<) and α-N-amidoalkyl (CON*C<) radicals.Both kinds of radicals have a clear-cut nucleophilic character and selectively attack protonated heteroaromatic bases, such as 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 hydrogen abstraction, aromatic substitution, and oxidation by Fe(III) salt is discussed.