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.