General procedure for the synthesis of methyl 2,2-dimethoxypropionate from methyl pyruvate and trimethyl orthoformate: 100 g (979 mmol) of methyl pyruvate was mixed with 135 g (1273 mmol) of trimethyl orthoformate in 240 ml of methanol. After adding 0.96 g (9.79 mmol) of concentrated sulfuric acid, the mixture was heated to reflux for 4 hours. Subsequently, the solvent was distilled out over 2 h. The crude product was cooled to 10 °C and added to a solution of 2.4 g of potassium hydroxide in 1200 ml of water at 10 °C. After repeated extraction with ether, the organic phases were combined and dried over anhydrous sodium sulfate, filtered and concentrated. The residue was distilled under reduced pressure and the fractions with boiling points of 50-55°C (10 mbar) were collected. Finally 118 g (77% yield) of the target product was obtained.1H NMR (CDCl3) data were as follows: δ = 1.53 (s, 3H, C-CH3), 3.29 (s, 6H, CH3-OCO-CH3), 3.82 (s, 3H, COOCH3).
