Action of potassium amide on 6‐substituted derivatives of 2‐bromopyridine in liquid ammonia

In continuation of previous studies on the reactions of 2‐bromo‐6‐ethoxy‐, 2‐bromo‐6‐methyl‐ and 2,6‐dibromopyridine with potassium amide in liquid ammonia, aminations of twelve other 2‐bromopyridines substituted at the 6‐position, i.e. 6‐amino‐, 6‐anilino‐, 6‐amidocarbonyl‐, 6‐(N‐methylanilino)‐, 6‐phenyl‐, 6‐(2′‐pyridyl)‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxy‐phenoxy)‐, 6‐(p‐fluorophenoxy)‐, 6‐chloro‐ and 6‐nitro‐2‐bromopyridine were investigated. The following reaction types were observed: Substitutions producing 2‐amino derivatives (from all starting substances except 6‐amino‐, 6‐bromo‐, 6‐chloro‐ and 6‐nitro‐2‐bromopyridine). Cine‐substitutions producing 4‐amino derivatives (from 6‐methyl‐, 6‐ethoxy‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxyphenoxy)‐ and 6‐(p‐fluorophenoxy)‐2‐bromopyridine). Ring transformations yielding 6‐substituted 2‐methylpyrimidines by fission of the 3,4‐carbon bond (from 6‐phenyl‐, 6‐(2′‐pyridyl)‐, 6‐phenoxy‐, 6‐(p‐ethoxyphenoxy)‐, 6‐(m‐ethoxyphenoxy)‐, 6‐(p‐fluorophenoxy)‐ and 6‐chloro‐2‐bromopyridine; from 2,6‐dibromopyridine). Replacement of the 6‐substituent producing the 6‐amino compound (from 2‐bromo‐6‐nitropyridine). Ring fission yielding 1, 3‐dicyanopropene by cleavage of the N —C6 bond (from 6‐amino‐2‐bromopyridine). The mechanisms of the reactions studied are discussed. In this connection the aminations of 2,6‐dichloro‐, 2,6‐difluoro‐ and 2‐amino‐6‐fluoropyridine were examined too.