Photocatalytic synthesis of imidazo[1,2-a]pyridines via C(sp)3–H functionalization using ethylarene as a sustainable surrogate of acetophenone and luminescence studies

Abstract

A metal-free method for synthesizing imidazopyridines utilizing ethylarene, 2-aminopyridine, and NBS under visible light using Eosin-Y as a photocatalyst has been developed. Eosin-Y activates and oxidizes the C–H bonds of ethylarene, followed by bromination and coupling with aminopyridine. This technique effectively transforms ethylbenzene and aminopyridine into desirable products, and it also employs catalytic amounts of the halogenating agent, which is continuously regenerated. This approach is suitable for biologically active compounds with luminescence properties due to its high atom efficiency, metal-free nature, environmental friendliness, and use of visible light as a renewable energy source. This journal is © The Royal Society of Chemistry, 2025