A Direct Route into Fused Imidazo-diazines and Imidazo-pyridines Using Nucleophilic Nitrenoids in a Gold-Catalyzed Formal [3 + 2]-Dipolar Cycloaddition

Pyridinium N-(heteroaryl)aminides can be employed as robust and practical synthetic equivalents of nucleophilic 1,3-N,N-dipoles in a formal cycloaddition onto electron-rich alkynes under gold catalysis. Convergent and regioselective access to five types of imidazo-fused heteroaromatics is provided from the appropriate aminide. The efficient transformation accommodates significant structural variation around the aminide, ynamide, or indolyl-alkyne reactants and tolerates sensitive functional groups.