Silver-Catalyzed [3+2] Cycloaddition of Azomethine Ylides with Isocyanides for Imidazole Synthesis

A silver-catalyzed aerobic oxidative [3+2] cycloaddition of azomethine ylides with aryl or heteroaryl isocyanides has been developed. The reaction represents a novel protocol for the efficient and practical synthesis of 1,2-diarylimidazoles bearing a broad range of substituents in good to excellent yields under mild conditions. The practicability of this cycloaddition was shown by a gram-scale synthesis and a double cycloaddition for the construction of highly conjugated polyarylimidazole systems.