Reagent/Substituent Switching Approach for the Synthesis of Substituted 1,3,4-Oxadiazole/1,3,4-Oxadiazoline and 1,2,4-Triazole Derivatives from N-Substituted Hydrazides

A metal-free method for the synthesis of substituted 1,3,4-oxadiazole/1,3,4-oxadiazoline and 1,2,4-triazole derivatives from a common starting material via reagent/substituent switching is reported. In the presence of 2-fluoropyridine/triflic anhydride, 1,3,4-oxadiazole derivatives were exclusively formed from N′-tert-butylhydrazides and 1,3,4-oxadiazoline derivatives were produced from N-phenylhydrazides. On the other hand, when using pyridine/triflic anhydride, salts of 1,2,4-triazoles were the sole products. (Figure presented.).