Preparation method of 2,5-dimethyl furan-3,4-dicarboxylate
A technology of diethyl diformate and dimethyl furan, which is applied in the field of preparation of organic compounds, can solve the problems of expensive reagents and high cost, and achieve the effects of simple and convenient operation, low cost and good application prospects
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Embodiment 1
[0019] Weigh 2,3-diacetylsuccinic acid diethyl ester (I) (243mg, 0.94mmol), add HCl solution (concentration: 0.4N, 3.3mL), heat and reflux under normal pressure microwave for 2 hours, cool to room temperature, diethyl ether Extract, collect the organic layer, wash with water and brine successively, dry over anhydrous sodium sulfate, filter, the filtrate recovers the solvent, and the residue is purified by flash column chromatography [eluting with petroleum ether-diethyl ether (5:1)] to obtain 2,5-Dimethylfuran-3-carboxylic acid ethyl ester (II) (colorless oil 51mg, yield 21%) and 2,5-dimethylfuran-3,4-dicarboxylic acid diethyl ester (IV ) (colorless oil 138mg, yield 61%).
[0020] Ethyl 2,5-dimethylfuran-3-carboxylate (II): 1 H NMR (CDCl 3 )δ: 1.33(t, 3H, J=7.1Hz), 2.36(s, 3H), 2.52(s, 3H), 4.26(q, 2H, J=7.1Hz), 6.21(s, 1H); 13 C NMR (CDCl 3 )δ: 13.2, 13.7, 14.5, 60.0, 106.3, 114.2, 150.0, 157.6, 164.4; consistent with literature reports (Wang Y et al. Org Lett, 2005, 7, 9...
Embodiment 2
[0023] Weigh 2,3-diacetylsuccinate diethyl (I) (184.7mg, 0.72mmol), add HCl solution (concentration: 1N, 1.2mL), heat and reflux under normal pressure microwave for 1 hour, cool to room temperature, diethyl ether Extract, collect the organic layer, wash with water and brine successively, dry over anhydrous sodium sulfate, filter, the filtrate recovers the solvent, and the residue is eluted by flash column chromatography [petroleum ether-diethyl ether (5:1) and then diethyl ether ] was purified to obtain ethyl 2,5-dimethylfuran-3-carboxylate (II) (colorless oil 24.0mg, yield 20%), 2,5-dimethylfuran-3,4- Dicarboxylic acid (III) (36.6mg of white crystals, yield 24%) and diethyl 2,5-dimethylfuran-3,4-dicarboxylate (IV) (90.0mg of colorless oil, yield 52%) ).
[0024] 2,5-Dimethylfuran-3,4-dicarboxylic acid (III): mp 214~216°; 1 H NMR (CD 3 COCD 3)δ: 2.60(s, 2×3H); 13 C NMR (CD 3 COCD 3 )δ: 14.5, 112.4, 161.5, 166.6; consistent with the measured data of commercially availabl...
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