Abstract
Alkylation of dienolates derived from crotonic and dimethylacrylic acids (2) by saturated or aromatic aldehydes and ketones (1) at low temperature affords 2-substituted-3-hydroxy-acids (3). The dianionic species of these isomerize on heating to (E)- and (Z)-unsaturated-5-hydroxy-acids (4) and (5), for crotonic and dimethylacrylic acids, respectively. Unsaturated ketones (6) suffer 1,4-addition through γ-alkylation, leading to (E)-unsaturated-7-oxo-acids (8) for both crotonic and dimethylacrylic acids. Unsaturated 5-hydroxy- and 7-oxo-carboxylic acids are readily prepared by the procedure here established.

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