ABSTRACT
A ultrasound-assisted oxidative cyclization of semicarbazones using N-bromosuccinimide in the presence of sodium acetate was established providing efficient and rapid access to a variety of 2-amino-1,3,4-oxadiazoles. Moreover, the new synthetic protocol provides a simple procedure utilizing a safer oxidizing system that affords the target products in high regioselectivity, satisfactory yields, and elevated purities.
GRAPHICAL ABSTRACT
![](/cms/asset/776512a2-921d-4058-86fc-c0482e177940/lsyc_a_1324626_uf0001_oc.jpg)
Acknowledgments
This work was supported by funds from the National Institute of Science and Technology on Tuberculosis (INCT-TB). L. A. Basso, D. S. Santos, and P. Machado are Research Career Awardees of the National Research Council of Brazil (CNPq). The fellowships from FAPERGS (A. F. Borsoi), CNPq (M. E. Coldeira), and CAPES (F. S. Macchi) are also acknowledged.