[Synthesis]
General procedure: 0.1 mole of 2,2-(dimethylthio)pentanoic acid (19.4 g) was dissolved in 150 mL of toluene, 2.0 equivalents of H2O (3.6 mL) and a trace amount of p-toluenesulfonic acid monohydrate were added. The mixture was heated to boiling point and a stream of nitrogen was passed through the glass feed. After refluxing for 3 hours and cooling to 80°C, 200 mL of ethanol and trace amounts of p-toluenesulfonic acid monohydrate were added. Reflow was continued for 3 hours, cooled to 20°C, 200 ml of water was added and extracted three times with diethyl ether (100 ml each time). The ether phases were combined, washed to neutrality with dilute sodium bicarbonate solution and dried over magnesium sulfate. After filtration, the solvent was removed by rotary evaporation to give ethyl 2-oxovalerate (10.2 g, 71% yield) as a light yellow oil.1H NMR (500 MHz, CDCl3): δ=0.97 (t, J=7.3 Hz, 3H), 1.37 (t, J=7.3 Hz, 3H), 1.67 (sext, J=7.3 Hz, 2H). 2.81 (t, J=7.3Hz, 2H), 4.32 (q, J=7.3Hz, 2H).13C NMR (125.8MHz, CDCl3): δ=13.5, 14.0, 16.6, 41.2, 62.3, 161.4, 194.7. |