Efficient Synthesis of 1‐Chloroimidazo[1,2‐a:4,5‐c']dipyridines, Versatile Synthons for Position‐1 Functionalisation with Various Reagents

In this work, the goal is to develop a versatile synthetic pathway to functionalize position‐1 of the imidazo[1,2‐ a ;4,5‐ c' ]dipyridine core. For this purpose, the synthesis of 1‐chloroimidazo[1,2‐ a ;4,5‐ c' ]dipyridines via a novel synthetic pathway starting from imidazo[1,2‐ a ]pyridines conveniently substituted with a carboxamide at position‐2 and an alkyne at position‐3 is described. This pathway involves a 6‐ endo ‐ dig cyclization leading to the 3‐alkyl‐1‐hydroxyimidazo[1,2‐ a ;4,5‐ c' ]dipyridine intermediates. The 1‐chloroimidazo[1,2‐ a ;4,5‐ c' ]dipyridines are then obtained via a dehydrochlorination. Further, their reactivity is evaluated, particularly in palladium‐catalyzed couplings and nucleophilic aromatic substitutions.