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.