ChemInform Abstract: Synthesis and Reactions of Some New Allyl Furobenzopyranone Derivatives

Reaction of visnaginone 1 with allyl bromide gave O-allyl visnaginone 2 which underwent Claisen rearrangement to yield 7-allylbenzofuran derivative 3. Reaction of 3 with different aromatic aldehydes gave the corresponding 5-cinnamoylbenzofuran derivatives 4a-d. Condensation of the latter chalcones 4a,c,d with hydrazine hydrate and phenylhydrazine provided, the corresponding pyrazoline derivatives 7a-f. Claisen condensation of compound 3 with ethyl acetate and diethyl carbonate afforded Claisen adducts 8 and 12 which easily cyclized to 9 and 13, which are endowed with interesting biological properties.