A one-pot telescopic approach has been developed for the safe, scalable, and efficient synthesis of substituted 2-arylimidazo1,2-apyridines starting from commercially available and inexpensive substituted acetophenones and 2-aminopyridine. The procedure involves the in situ formation of phenacyl bromides via chemoselective bromination of acetophenones with N-bromosuccinimide, followed by nucleophilic substitution and heterocyclization with 2-aminopyridine to yield 2-arylimidazo1,2-apyridines. This streamlined telescopic method avoids handling and isolation of hazardous and lachrymatory phenacyl bromides. Moreover, this synthetic protocol eliminates unit operations such as solvent extraction, solvent evaporation/distillation, and final product purification. Notably, the practical utility of this telescopic approach has been demonstrated on a gram scale, affording the product in good yields.
Deshmukh et al. (Sun,) studied this question.