1,3,4-Oxadiazoles by Ugi-Tetrazole and Huisgen Reaction.

Easy to perform, functional group tolerant, and short syntheses of the privileged scaffold oxadiazole are highly desired. Here, a metal-free protocol for MCR-based synthesis of 2,5-disubstituted 1,3,4-oxadiazoles via a Ugi-tetrazole/Huisgen sequence was developed. Optimization and scope and limitations of this short and general sequence are described. The reaction was also successfully performed on a gram scale.