Mesityl ketones, conjugate addition

The conjugate addition of hydrogen cyanide, generated in situ from KCN and acetic acid to (i-mesityl ketones, gives high yields of the corresponding oxo nitriles in aqueous ethanol (Eq. 10.19).41... 

Dimedone has a trivial name because its preparation is so easy that it was discovered early in the history of organic chemistry. The first step is a conjugate addition of diethyl malonate to the unsaturated ketone mesityl oxide (4-methylpent-3-en-2-one given a trivial name for the same reason). Ethoxide ion is the base for the usual reason that nucleophilic substitution at the ester group simply regenerates starting material. 

The first conjugate addition reaction to be observed in this series was with mesityl phenyl ketone and the phenyl reagent. The product, obtained in a yield of 18%, was 2-mesitoylbiphenyl (29). 

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