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Abstract
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The reaction of aromatic aldehydes, dimedone, and malononitrile in the presence of ammonium acetate has afforded tetrahydrobenzo[b]pyrans instead of polyhydroquinolines under both grinding and reflux conditions; thus ammonium acetate acts as a catalyst for this transformation instead of a reactant. Polyhydroquinoline derivatives were also synthesized via a one-pot condensation of aromatic aldehydes, malononitrile and an enaminone, which was prepared by the reaction of dimedone and ammonium acetate, in refluxing ethanol in high yields.
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