Switching of Regioselectivity in a Perfluorohexyl Iodide Mediated Synthesis of Phenylimidazo[1,2‐<i>a</i>]pyridines

Abstract

3‐Phenylimidazo[1,2‐ a ]pyridines were synthesized through the perfluorohexyl iodide mediated coupling of 2‐aminopyridines and phenylacetylenes. In situ iodination of the terminal alkyne by perfluorohexyl iodide reverses the polarity by generating a transient electrophilic iodoalkyne, and this alters the regioselectivity of the phenyl group. The reaction then proceeds by tandem electrophilic alkynylation and cyclization to form the fused‐ring product. The protocol affords the 3‐phenyl isomer with full regioselectivity and is complementary to reported methodologies for the synthesis of the 2‐phenyl isomer starting from the same substrates.