Abstract
The condensation of 3-acetyl coumarin (1) with aromatic aldehydes in presence of a base to yield 3-cinnamoyl coumarin derivatives (2a-e). The latter compounds reacted with phenyl hydrazine and hydrazine hydrate in refluxing ethanol to yield 3-[5-aryl-1-phenyl-pyrazolin-3-yl] (3a-e) and 3-[5-aryl-1H-pyrazolin-3-yl] (4a-e) coumarin, respectively. Reaction of compounds 2a-e with hydrazine hydrate in refluxing acetic acid gave the N-acetyl derivatives 5a-e. Also, the reaction of 2a-e with hydroxylamine hydrochloride in presence of a base led to the formation of the oximes 6a-e. Epoxidation of compounds 2a-e using hydrogen peroxide in alkaline medium gave the corresponding epoxypropanonyl derivatives 7a-e.
Compound W reacted with semicarbazide hydrochloride in presence of sodium acetate to give the semicarbazone (0) which was subjected to oxidative cyclization using selenium dioxide in acetic acid to give 3-(1,2,3-selenadiazol-4yl) coumarin (2); Moreover the oxidative cyclization of (8) by thionyl chloride yielded 3-(1,2,3-thiadiazol-4-yl) coumarin (10).