Improved Synthetic Process of Dimethyl 4‑Oxo‑4H‑pyran-3,5-dicarboxylate

A reported two-step procedure for preparing dimethyl 4-oxo-4H-pyran-3,5-dicarboxylate was extensively optimized. It was found that the reactions can be carried out in toluene as a single solvent and the product was directly obtained by a simple filtration. More importantly, considering potential solvent recovering and recycling, the effluent of the process can be remarkably reduced. This new process facilitated the potential scale-up with commercial significance.