The synthesis of bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides and other related 1,3,4-oxadiazoles from 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters

Reactions of symmetrical 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters in the presence of catalytic amount of glacial acetic acid resulted in the formation of three heterocyclic products: the appropriate bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides, 2-benzyl-1,3,4-oxadiazoles and 2-benzoyl-1,3,4-oxadiazoles. The presence of the latter two compounds is connected with carbon–sulfur fission in the molecule of the starting hydrazide. The identity of the unexpected fission products was confirmed by parallel syntheses of the model 1,3,4-oxadiazoles from phenylacetic acid hydrazide and 2-hydroxymethyl-1,3,4-oxadiazole derivatives.