[CH3:1][C:2](=[O:6])[C:3](=[O:5])[CH3:4].CN(C1C=CC=CN=1)C.C(N(CC)CC)C.[C:23](OC(=O)C)(=[O:25])[CH3:24]>CCOCC>[C:23]([O:5][C:3](=[CH2:4])[C:2](=[O:6])[CH3:1])(=[O:25])[CH3:24]To a solution of 19.6 g. (228 mol) of 2,3-butanedione in 200 ml. of ether was added 3.34 g. (27 mmole) of dimethylamino pyridine, and 23 g. (228 mmole) of triethylamine. The solution was cooled to 0° and 23.24 g. (228 mmol) of acetic anhydride was added dropwise with vigorous stirring. The clear yellow solution was allowed to warm to 25° and was stirred 3 hours. The reaction mixture was transferred to a separatory funnel, washed with water (3×) and dried over MgSO4. Filtration and evaporation in vacuo afforded 17.6 g. of crude 3-acetoxy-3-buten-2-one (assayed by 1H-NMR with internal standard as 91% pure, 56% yield): 1H-NMR (CDCl3) delta 2.06 (s, 3), 2.25 (s, 3), 5.42, 5.49, 5.79, 5.82 (AB, 2).
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