Sonogashira reaction on pyridinium N-haloheteroarylaminides: regioselective synthesis of N-alkyl-3-alkynyl-5-arylpyridin-2-yl amines

A study of Sonogashira copper-free coupling processes on pyridinium N-iodoheteroarylaminides has been performed. A regioselective strategy starting from 3-bromo-5-substituted N-(pyridin-2-yl)pyridinium aminides and including N-alkylation, N–N bond reduction and a final Sonogashira reaction gave rise to a series of N-alkyl-3-alkynyl-5-arylpyridin-2-yl amines.