Acetylene-driven multi-molecular assemblies of high complexity: imidazo[1,2-a]pyridines and 5-chloro-N-[2-(imidazo[1,2-a]pyridin-6-yl)vinyl]pyridin-2-amine

Acetylene reacts with 2-aminopyridines in the superbase system KOBu^t/DMSO (the initial acetylene pressure ∼8 atm, 80 °C, 5 min) to give 2,3-dimethylimidazo[1,2-α]-pyridines in up to 60% yields. In the case of 2-amino-5-chloropyridine, along with ‘normal’ product, (Z)-5-chloro- N-[2-(2,3-dimethylimidazo[1,2-α]pyridin-6-yl)vinyl]pyridin-2-amine is formed in 40% yield. These multi-molecular assemblies involve parallel nucleophilic addition of N-centered anions to the triple bond and ethynylation of the forming C=N bond.