Phenylhydrazones, Boulton-Katritzky rearrangement

The 1H, 13C, and 15N NMR chemical shifts of the (Z)-phenylhydrazones of 5-alkyl-and 5-aryl-3-benzoyl-l,2,4-oxadiazoles have provided information on the ground-state electronic distribution.27 The effects of the substituents on the chemical shifts of N(4) and C(5) correlate with kinetic results of the rearrangement of 1,2,4-oxadiazoles to 1,2,3-triazoles (Boulton-Katritzky reaction) support the importance of the leaving group. 

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