A process for preparing Z-5-carboxymethylene-1,3-dioxolan-4-ones is provided which includes the steps of reacting a bis-ketal or bis-acetal of tartaric acid with a potassium containing base to form the carboxymethylene-1,3-dioxolan-4-one. A process for preparing HIV integrase inhibitors employing the carboxymethylene-1,3-dioxolan-4-one inhibitor is also provided.