Synthesis and characterization new schiff bases, pyrazole and pyrazoline compounds derived from acid hydrazide containing isoxazoline ring

Abstract EN

The work involves synthesis of new Schiff bases ([V]a, b and [VI]a, b), pyrazoles [VII]a, b and pyrazolines [VIII]a, b derivatives containing isoxazoline unit starting with chalcones.

4-bromoacetophenone was reacted with 4-hydroxybenzaldehyde or 4-hydroxyacetophenone was reacted with 4-bromobenzaldehyde in basic medium to give chalcone by Claisen-Schemidt reaction.

The chalcons [I] a, b was reacted with hydroxylamine hydrochloride to form isoxazolines [II] a, b.

which were reacted with ethyl chloro acetate in basic medium to get ester compounds [III] a, b.

The condensation new ester [III] a, b with hydrazine hydrate 80 % yieldedacid hydrazide [IV] a, b.

The later compound refluxing with 4-substituted benzaldehyde in dry benzene to give Schiff bases ([V]a, band [VI]a, b) while the reaction of acid hydrazide [IV]a, b with acetylacetone or ethyl aceto acetate to get pyrazole [VII]a, b, pyrazolone [VIII]a, b, respectively.

The synthesized compounds were characterized by melting points, FTIR, mass and 1H NMR spectroscopy (of someof them).