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With 1,1'-carbonyldiimidazole; In tetrahydrofuran; |
(1) Carbonyldiimidazole (8.7 g, 30.4 mmol) was added to a solution of 4-nitrophenylacetic acid (10 g, 55.2 mmol) in tetrahydrofuran (100 ml) at room temperature. After stirred at room temperature for 6 hours, a magnesium salt of malonic acid monoethyl ester (4.4 g, 15.2 mmol) was added. This mixture was stirred at 60 C. for 1.5 hours, The reaction solution was diluted with ethyl acetate (100 ml), washed with 1N hydrochloric acid, an aqueous saturated sodium bicarbonate solution and saturated brine, dried with sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography [eluent:hexane-ethyl acetate (3:1)] to obtain ethyl 4-(4-nitrophenyl)-3-oxobutanoate (10.3 g, 41.0 mmol, 74%) as a pale yellow powder. IR numax (KBr) cm-1: 1738, 1722 (C=O). 1H-NMR (CDCl3) delta: 1.280 ({fraction (1/7)}*3H, t, J=7.0 Hz), 1.289 ({fraction (6/7)}*3H, t, J=7.0 Hz), 3.529 ({fraction (6/7)}*2H, s), 3.603 ({fraction (1/7)}*2H, s), 4.000 ({fraction (6/7)}*2H, s), 4.194 ({fraction (1/7)}*2H, q, J=7.0 Hz), 4.216 ({fraction (6/7)}*2H, q, J=7.0 Hz), 4.973 ({fraction (1/7)}*1H, s), 7.36-7.46 (2H, m), 8.17-8.24 (2H, m). Elemental Analysis (C12H13NO5) Cal'd: C, 57.37; H, 5.22; N, 5.58. Found: C, 57.42; H, 5.13; N, 5.72. |