Cu-Catalyzed Chan-Evans-Lam Coupling Reactions of 2-Nitroimidazole with Aryl Boronic Acids: An Effort toward New Bioactive Agents against S. pneumoniae.

The coupling of phenylboronic acids with poorly-activated imidazoles is studied as a model system to explore the use of copper-catalyzed Chan-Evans-Lam (CEL) coupling for targeted C-N bond forming reactions. Optimized CEL reaction conditions are reported for four phenanthroline-based ligand systems, where the ligand 4,5-diazafluoren-9-one (dafo, L2) with 1 molar equivalent of potassium carbonate yielded the highest reactivity. The substrate 2-nitroimidazole (also known as azomycin) has documented antimicrobial activity against a range of microbes.