Total synthesis method for preparing receme alkannin
A technology for total synthesis of shikonin, applied in the preparation of quinone oxide, bulk chemical production, organic chemistry, etc., can solve the problems of low reaction yield, harsh reaction conditions, high price, etc., and achieves high reaction yield and synthesis. The effect of few steps and easy availability of raw materials
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Embodiment 1
[0017] Example 1: 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene
[0018] Under the protection of nitrogen at room temperature, put in 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde (0.01mol) and hexamethyltriphosphoramide (0.50mol), drop the preprenyl bromide already prepared Zinc chloride reagent (0.50 mol). After reacting for 1 hour, evaporate tetrahydrofuran, react at 130°C for 72 hours, cool after reaction, hydrolyze with 200ml saturated ammonium chloride aqueous solution, extract with 300ml / 3 ethyl acetate, wash with brine, dry over anhydrous magnesium sulfate, evaporate The solvent was removed to obtain a crude product, which was subjected to column chromatography to obtain 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene with a yield of 86.4%. 1 HNMR (CDCl 3 )δ=7.02(s, 1H, ArH), 6.82(d, 1H, ArH), 6.80(d, 1H, ArH) 5.22-5.26(m, 2H, CHOH and C=CH), 3.94(s, 3H, OCH 3 ), 3.93 (s, 3H, OCH 3 ), 3.89 (s, 3H, OCH 3 ), 3.75(s, 3H, OCH 3...
Embodiment 2
[0019] Example 2: 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene
[0020] Under the protection of nitrogen at room temperature, put in 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde (0.01mol) and N-methylpyrrolidone (0.15mol), drop the prepared isopentyl bromide Zinc reagent (0.15 mol). After reacting for 2 hours, evaporate tetrahydrofuran, react at 150°C for 24 hours, cool after reaction, hydrolyze with 20ml saturated ammonium chloride aqueous solution, extract with ethyl acetate 30ml / 3, wash with brine, dry over anhydrous magnesium sulfate, evaporate The solvent was removed to obtain a crude product, which was subjected to column chromatography to obtain 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene with a yield of 81.9%. 1 The H-NMR data is consistent with Example 1.
Embodiment 3
[0021] Example 3: 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene
[0022]Under the protection of nitrogen at room temperature, 1,4,5,8-tetramethoxynaphthalene-2-carbaldehyde (0.01mol) and 1,3-dimethylimidazolidinone (0.05mol) were added dropwise to the prepared Isopentenyl zinc bromide reagent (0.05 mol). After reacting for 4 hours, distill THF, react at 100°C for 10 hours, cool after reaction, hydrolyze with 50ml of saturated ammonium chloride aqueous solution, extract with 100ml / 3 ethyl acetate, wash with brine, dry over anhydrous magnesium sulfate, evaporate The solvent was removed to obtain a crude product, which was subjected to column chromatography to obtain 2-(1-hydroxy-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene with a yield of 83.0%. 1 The H-NMR data is consistent with Example 1.
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