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Synthetic routes to obtain coumarin-based compounds. Reaction conditions: (a) hydrazine solution, corresponding aldehyde, in ethanol refluxed; (b) N,N-dimethylamino-p-benzaldehyde, piperidine catalytic amounts, in ethanol; and (c) semicarbazide or thiosemicarbazide, aqueous-ethanolic solution (1:1), acetic acid catalytic amounts.
