Gold-Catalyzed Formal [3 + 2] Cycloaddition of Ynamides with 4,5-Dihydro-1,2,4-oxadiazoles: Synthesis of Functionalized 4-Aminoimidazoles.

A gold-catalyzed formal [3 + 2] cycloaddition of ynamides with 4,5-dihydro-1,2,4-oxadiazoles has been developed. The reaction provides a concise and regioselective access to highly functionalized 4-aminoimidazoles likely via the formation of an α-imino gold carbene intermediate followed by cyclization. 4,5-Dihydro-1,2,4-oxadiazole was found to act as an efficient N-iminonitrene equivalent in these reactions.