Synthesis and reactions of some 3-cyano-4-methylcoumarins

Abstract

o-Hydroxy ketones (I) were converted into 3-cyano-4-methylcoumarins (II) via condensation with ethyl cyanoacetate in presence of piperidine or ammonium acetate as a catalyst. The behavior of compound (II) towards Grignard and Michael reactions was investigated. The reactions of 3-acetylcoumarin (III) with hydrazines under different conditions were carried out to give the hydrazone (IV a), phenylhydrazone (IV b) and pyrazole (V) derivatives. Also, the 4-styryl derivatives (VI) were obtained by condensation of II with different aromatic and heterocyclic aldehydes. A one pot synthesis of Michael product (VII) from the reaction of VI with malononitrile was described. © 1993.