A reported synthesis of di-ester involves the SN2 displacement of 5-(chloromethyl)-2-furfuraldehyde with phthalic acid dipotassium salt. See Chundury, D.; Szmant, H. H. Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, pp. 158-163. This method has moderate yields (65%) and results in the production of tar-like impurities which can only be efficiently removed by column chromatography. Reproduction of these reported experimental procedures under optimal conditions generated the desired compound in low yield with extensive impurities. These impurities appear to extend from the decomposition of 5-(chloromethyl)-2-furfuraldehyde. See Sanda, K.; Rigal, L.; Delmas, M.; Gaset, A. Synthesis 1992, 6, pp. 541-542.
The present invention provides new methods for production.