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With phosphorus tribromide; triethylamine; In toluene; at -78 - 20℃; |
In a 100 mL round bottom flask, phytol (trans: cis (2:1) isomeric mixture of 34.9 mL, 100 mmol) and triethylamine (1.4 mL, 10 mmol) were added to toluene (100 mL), the reaction mixture was cooled down to -78 0C. Phosphorus tribromide (4.7 mL, 50 mmol) was added dropwise. After addition complete, the reaction mixture was warmed up to room temperature and stirred for 4 hours. Water (100 mL) was added dropwise to quench the reaction. Ethyl acetate (200 mL) was added and then washed with water (50 mL x 2) and brine (50 mL x 2) sequentially. The ethyl acetate solution was dried by Na2SO4 and concentrated in vacuo. The resulting residue was directly used for the next reaction. L-cysteine hydrochloride monohydrate (1.90 g, 10.73 mmol) and potassium carbonate (2.96 mg, 21.45 mmol) were added to ethanol (40 mL) and water (40 mL), the reaction was stirred at room temperature for 30 min, phytyl bromide (2.56 g, 7.15 mmol) was added. The reaction mixture was stirred at room temperature under argon for 4 hours. The precipitate obtained was washed by water, ethanol and dry in vacuum for 72 hours. White solid obtained was product which was directly used for the next reaction. Mono-methyl succinate (132 mg, 1 mmol), 2~S7-Aza-1 H-be?zotriazole- l -y[)-lj ,.}53-tetramelhy[urotiium hexalluoropho^phate ( 1.1 mg, 1.1 mmol) and N5N- diisopropyl-ethyl-amine (0.52 mL, 3 mmol) were mixed in THF (5 mL). The reaction solution was stirred at room temperature for ten minutes. 2-Amino-3-(3,7,l 1,15-tetramethyl- hexadec-2-enylsulfanyl)-propionic acid (399 mg, 1 mmol) was added to reaction mixture. The reaction solution was stirred at room temperature overnight. Ethyl acetate (50 mL) was added and then washed with saturated ammonium chloride aqueous solution (20 mL x 2), DI water (20 mL x 2) and brine (20 mL x 2) sequentially. The ethyl acetate solution was dried by Na2SO4 and concentrated in vacuo to afford a crude mixture of 1 : 1 trans isomers and 1 : 1 cis isomers of compound N-53, wherein the ratio of trans isomers to cis isomers is 7:3 (200 mg, 40%). 1H-NMR (500 MHz, MeOH-d4): delta 0.76-0.79 (m, 12H), 1.00-1.46 (m, 19H), 1.58 and 1.63 (s, 3H), 1.91-1.99 (m, 2H), 2.48-2.52 (m, 4H), 2.60-2.64 (m, IH), 2.87 (dd, J = 4.5, 14.0 Hz, IH), 3.04-3.07(m, IH), 3.14-3.18 (m, IH), 3.57 (s, 3H), 4.46-4.49 (m, IH), 5.12 (t, J = 7.5 Hz, IH). 13C-NMR (125 MHz, MeOH-d4): delta 20.12, 20.17, 20.23, 23.05, 23.14, 23.59, 25.52, 25.94, 25.96, 26.30, 26.31, 26.64, 29.19, 30.20, 30.40, 31.26, 32.87, 33.54, 33.79, 33.82, 33.88, 33.94, 33.97, 37.62, 37.71, 38.41, 38.50, 40.56, 40.95, 52.27, 53.40, 53.53, 121.43, 121.89, 140.87, 141.01; ES-MS: mass calcd for Chemical Formula: C28H5INO5S 513.3. Found (M+Na) m/z 536.3. |
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With carbon tetrabromide; triphenylphosphine; In dichloromethane; at 20℃; for 2h; |
Phytyl bromide can be obtained by the implementation of the following stages: Into a lapped-column flask, introduce: phytol (10 mmol) and dichloromethane that contains triphenyl phosphine; an excess of 20 to 30% is necessary for entirely consuming the phytol, Stir with a magnet, Add carbon tetrabromide all at once; the solution that is obtained is clear and slightly light yellow, Allow to react for 2 hours at ambient temperature. Next, the purification of the reaction medium is carried out by liquid-liquid extractions: Add 50 ml of an NaHCO3-saturated solution, Stir and eliminate the aqueous phase, Wash the organic phase with distilled water, Stir and eliminate the aqueous phases, Dry-evaporate the organic phase under a stream of nitrogen, Take up the dry residue with hexane or cyclohexane, Filter the hexane phase on a Whatman filter, Wash the precipitate with hexane or cyclohexane, and then Dry-evaporate the hexane or cyclohexane. An orangey oily residue is obtained. |
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