Synthesis of some potentially bioactive compounds from visnaginone

The reaction of 5-acetyl-6-hydraxy-4-methoxybenzo[b]furan (visnaginone Ia) with 2-diethylaminoethylchloride fed to the formation of 5-acetyl-6-diethyl amino-ethoxy-4-methoxybenzo[b]furan (II), whereas condensation of compound H with some aromatic aldehydes afforded the corresponding chalcones IIIa-c. Methylation of visnaginone (Ia) gave 5-acetyl-4,6-dimethoxybenzo[b]furan ( Ib), which in turn rr:acted with some aromatic aldehydes to give the corres ponding chalcones IIId,e. The reaction af chalcones IIId,e with hydrazine h ydrate in alcohol gave the pyrazoline derivatives nra,b, whereas when the s ame reaction was carried out in acetic acid it: afforded the N-acetylpyrazo line derivatives Va,hi. Similarly, the reaction of IIId,e with phenyl hydra zine in acetic acid led to the formation of phenylpyrazoline derivatives VI a,b, whereas condensation of chalcones IIId,e with hydroxyl amine hydrochlo ride: gave the isoxazoline derivatives VIIa,b. The reaction of compound II with phenylhydrazine and 2,4,6-trichlorophenylhydrazine le afforded the cor responding phenyl hydrazone derivatives VIIIa,b. Mannich bases IXa,b were s ynthesized by the reaction of visnaginone (Ia) with piperidine and benzylar nine in the presence of formaline.