Pd(II)‐Catalyzed Dehydrogenative Annulation of 2‐Arylimidazo[1,2‐a]pyridines with Maleimides: Regioselectivity Switch and Photophysical Properties

Herein, we report a palladium(II)-catalyzed dehydrogenative annulation of 2-arylimidazo[1,2-a]pyridines with maleimides, representing the first example of the regioselectivity reversal for this class of substrates. Notably, the transformation proceeds efficiently with a low catalyst loading (1.5 mol %). A plausible reaction mechanism is proposed, supported by control experiments and in situ HRMS analysis. Photophysical investigations of the annulated products reveal moderate to high quantum yields, highlighting their potential for optoelectronic applications. Furthermore, these molecules demonstrate promising sensitivity as picric acid-sensing probes.