Reaction of Aliphatic Ketones with α-Cyano-α, β-unsaturated Acid Derivatives

Abstract

Abstract The reaction of several aliphatic ketones with α-cyano-α, β-unsaturated acid derivatives has been studied. Ethylidenecyanoacetic acid reacted with a large excess of acetone in an autoclave at 150–160°C to give 3-methyl-5-oxohexanonitrile, which was considered to be produced by the decarboxylation of the Michael-type adduct of acetone onto the acid. Similar adducts were obtained by the reaction of the acid with methyl ethyl ketone, cyclohexanone, and ethyl laevulinate. The reaction of ketones with ethyl ethylidenecyanoacetate did not afford Knövenagel-type condensates, but Michael-type adducts in appreciable yields, for example, ethyl 2-cyano-3,4-dimethyl-5-oxohexanoate from methyl ethyl ketone. Diethyl ethylidenemalonate also gave Michael-type adducts. These results seem to suggest that the γ-methyl group of ethylidenecyanoacetic acid or its ester is not active enough to give Knövenagel-type condensates with aliphatic ketones, and that, therefore, the Knövenagel-type reaction is preceded by the Michael-type addition reaction of ketones onto the activated carbon-carbon double bond.