Reactions of hydroxybenzofurans. VI. Syntheses of benzofuran chalcones, hydrazones and pyrazolines of potential biological activity.

Condensation of 5-acetyl-6-methoxy- (I) and 6-acetyl-5-methoxy-2,3-diphenylbenzofuran (II) with aromatic aldehydes gave the chalcones IIIa--f and IVa--f, respectively. Reaction of the chalcones IIIa--f and IVa--f with hydrazine hydrate-acetic acid mixture yielded the corresponding N-acetyl pyrazolines Va--f and VIa--f. The chalcones IIIa--f and IVa--f reacted with phenylhydrazine in ethanol to yield the corresponding phenylhydrazones VIIa--f and VIIIa--f. The latter hydrazones cyclize easily with boiling glacial acetic acid to the corresponding pyrazoline derivatives (IXa--f and Xa--f). The antibacterial activity of the chalcones and pyrazolines was investigated.