Ruthenium(II)-Catalyzed C–H/N–H Alkyne Annulation of Nonsymmetric Imidazoles: Mechanistic Insights by Computation and Photophysical Properties

Imidazoles constitute an important class of heterocyclic compounds with extensive potential use, from pharmaceuticals to optoelectronics. However, synthetic methodologies capable of producing novel nonsymmetric imidazoles are still scarce. In a combined synthesis, photophysical and computational investigation, we show that ruthenium(II) catalysis enables C−H/N−H alkyne annulation of nonsymmetric imidazoles derived from naturally occuring β-lapachone and nor-β-lapachone. This method provides an efficient and versatile tool for synthesizing fluorescent compounds with a broad application range.