Abstract
2-Phenyl-6-styryl-4-pyrone derivatives have been synthesised from the reaction of ethyl phenylpropiolate with benzylideneacetone derivatives in the presence of sodium ethoxide. Treatment of styrylpyrone with phosphorus pentasulfide gave the corresponding styrylpyran-4-thione which on treatment with hydroxylamine hydrochloride and aqueous methylamine afforded the corresponding oxime and 1-methyl-2-phenyl-6-styrylpyridine-4(1H)-thione, respectively. On the other hand, styrylpyran-4-thione reacted with malononitrile to give pyrolylidenemalononitrile which on treatment with bidentate reagents, hydrazine hydrate, hydroxylamine hydrochloride, thiourea, and thiosemicarbazide afforded the corresponding styrylspiropyran derivatives of pyrazole, 1,2-oxazole or 1,3-thiazine, respectively.