[OH:1][C:2]([CH3:7])([CH3:6])[C:3](=[O:5])[CH3:4].C(N(CC)CC)C.[C:15](OC(=O)C)(=[O:17])[CH3:16].CO>ClCCl.CN(C)C1C=CN=CC=1.CCOCC>[CH3:6][C:2]([O:1][C:15](=[O:17])[CH3:16])([CH3:7])[C:3](=[O:5])[CH3:4]A solution of 3-hydroxy-3-methyl-2-butanone (10.75 ml, 100 mmol) and triethylamine (21 ml, 150 mmol) in dichloromethane (125 ml) was treated with acetic anhydride (11.8 ml, 125 mmol) then with 4-dimethylaminopyridine (610 mg, 5 mmol) and the reaction was stirred at ambient temperature for 14 h. Methanol (10 ml) was added and stirring continued for 30 min before concentrating the reaction in vacuo. The residue was dissolved in ether (300 ml) and washed with 0.5N hydrochloric acid (2×300 ml), water, saturated aqueous sodium hydrogencarbonate, dried over anhydrous magnesium sulfate, filtered and evaporated to dryness to afford acetic acid 1,1-dimethyl-2-oxopropyl ester as a yellow liquid (13.5 g, 94%): δH (400 MHz, CDCl3) 1.46 (6H, s), 2.09 (3H, s), 2.12 (3H, s).
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