Mechanisms for the Benzoylation of 2-Aminopyridine

Abstract

Relative rate studies on ring methyl-substituted derivatives of 2-aminopyridine in pyridine solvent show that reaction with benzoyl chloride gives monobenzoyl derivatives by direct reaction on the exocyclic nitrogen (N'). The reaction is analogous to acetylation with acetic anhydride. Reaction in acetone, however, gives, except for the 6-methyl compound, N',N?-dibenzoylamino compounds, even in the presence of excess of amine. The results are shown to be consistent with ring nitrogen benzoylation (N1), followed by rapid N'-benzoylation and intramolecular benzoyl rearrangement from N1 to N'.