Reactivity of Z- and E-isomers of 2-benzamido-3-phenylacrylohydrazide towards some carbon electrophiles. A comparative study

Z- and E-isomers of 2-benzamido-3-phenylacrylohydrazide 2a, 2b have different relative reactivities towards some carbon electrophiles had been discussed.The Z-isomer underwent cyclization to give imidazole derivative 3 and triazine derivative 4, whereas the latter E-isomer does not undergo such cyclization. The reaction of 2a and/or 2b with 1,2-dibenzylidene hydrazine at different reaction conditions afforded the Schiff bases 6, 8 and the triazolidine derivative 9. Reactions of 2a, 2b with formic acid and phthalic anhydride gave the different cyclization products 10–14, respectively. The structures of all the new synthesized compounds were established from their IR, ¹H-NMR and mass spectra as well as elemental analyses.