Process for producing optically pure δ - hydroxy-β -ketoester derivatives

The present invention relates to a process for producing optically pure δ-hydroxy-β-ketoester derivatives comprising the steps of: Reacting a chiral 3,4-substituted butyric acid derivative of formula (2) and meldrum's acid of formula (3)in a mild condition and the presence of a base to produce acyl meldrum's acid of formula (4), and Heating at reflux in an alcohol to obtain an optically pure δ-hydroxy-β-ketoester derivative of formula (1).