Synthesis of 3,5-disubstituted-1,2,4-oxadiazoles using tetrabutylammonium fluoride as a mild and efficient catalyst

Tetrabutylammonium fluoride (TBAF) was found to be a mild and efficient catalyst for the synthesis of 3,5-disubstituted-1,2,4-oxadiazoles. Using 0.1–1.0 equivalents of TBAF in THF for 1–24 h at room temperature, alkanoyl- and aroyloxyamidines were converted in high yield to the corresponding 3,5-disubstituted-1,2,4-oxadiazoles. A variety of R and R′ substituents were investigated.