S. Liras et al., A mild method for the preparation of 1,3,4-oxadiazoles: Triflic anhydride promoted cyclization of diacylhydrazines, SYN COMMUN, 30(3), 2000, pp. 437-443
Diacylhydrazines undergo cyclization upon treatment with triflic anhydride
and pyridine to form the corresponding 1,3,4-oxadiazoles in yields ranging
from 70-95%.