Synthesis, anti-inflammatory, analgesic and anticonvulsant activities of some new 4,6-dimethoxy-5-(heterocycles)benzofuran starting from naturally occurring visnagin

Novel 3-(4,6-dimethoxybenzofuran-5-yl)-1-phenyl-1H-pyrazole-4-carboxaldehyde (3) and 3-chloro-3-(4,6-dimethoxybenzofuran-5-yl)propenal (4) were prepared via Vilsmeier–Haack reaction of 1-(4,6-dimethoxybenzofuran-5-yl)ethanone (1) and its hydrazone derivative 2. Reaction of compound 4 with some hydrazine derivatives, namely hydrazine hydrate, phenylhydrazine and benzylhydrazine hydrochloride led to the formation of pyrazole derivatives 5–8, respectively. On the other hand, reaction of compound 4 with thiourea, urea or guanidine gave the pyrimidine derivatives 9–11, respectively. Reaction of amino compound 11 with acetic anhydride, benzoyl chloride and benzenesulphonyl chloride yielded N-substituted pyrimidine derivatives 12–14, respectively. Reaction of diazonium salt of compound 11 with sodium azide afforded azidopyrimidine derivative 15, which upon reaction with ethyl acetoacetate gave 1,2,3-triazole derivative 16. Acid catalyzed reaction of 11 with p-nitrobenzaldehyde gave Schiff base 17, which cyclized upon reaction with thioglycolic acid or chloroacetyl chloride to give thiazolidin-4-one 18 and azetidin-2-one 19, respectively. The newly synthesized compounds were tested for their anti-inflammatory, analgesic and anticonvulsant activities. Depending on the obtained results, the newly synthesized compounds possess significant anti-inflammatory, analgesic and anticonvulsant activities.