溴基-三聚乙二醇-丙酸叔丁酯

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Alternatively, 1.61 g (5.03 mmol) of 9a was co-evaporated successively with 100% ethanol and toluene, then dried over anhydrous sodium sulfate and 4A molecular sieves in dichloromethane. The mixture was filtered and concentrated. To the dried compound (1.42 g) in 20 ml of dichloromethane was added 2.48 g of carbontetrabromide (CBr4, 7.47 mmol) and 1.50 g of triphenylphosphine (PPh3, 5.71 mmol). After stirring under an atmosphere of argon overnight, the reaction mixture was filtered through a silica gel bed, then concentrated and purified by silica gel chromatography. (EtOAc/Hexane Gradient starting at a ratio of 1:2 and changing to a ratio of 2:3) to yield 0.92 g of the 10a. (62%). Rf=0.64 (EtOAc); 1H NMR (CDCl3) 3.785 (t, 2H, J=6.3+6.3 Hz), 3.68 (t, 2H, J=6.5+6.5 Hz), 3.650 (m, 8H), 3.615 (m, 4H), 3.462 (t, 2H, J=6.3+6.4 Hz), 2.491 (t, 2H, J=6.5+6.5 Hz), 1.434 (s, 9H); 13C NMR 171.063, 80.656, 71.368, 70.831, 70.764, 70.706, 70.678, 70.545, 67.061, 36.431, 30.474, 28.263; MS m/z 408.74 (M+Na)+, 406.70, 405.70, 404.73. dried over anhydrous sodium sulfate and 4A molecular sieves in dichloromethane The mixture was filtered concentrated the reaction mixture was filtered through a silica gel bed concentrated purified by silica gel chromatography

反应条件: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: To a stirred solution of 9a (1.0 g, 3.11 mmol) in 1 mL of pyridine at 0° C. was slowly added phosphorus tribromide (0.116 mL, 1.22 mmol) via syringe (Bradshaw et al., J. Het. Chem., 27:347-349 (1990)). The solution was allowed to stir overnight, at which time TLC analysis indicated that the reaction was complete. Water (25 mL) was poured into the reaction vessel and the organics were extracted into methylene chloride (3×25 mL). The combined organic layers were washed with sodium bicarbonate (25 mL), followed by brine (25 mL), dried over magnesium sulfate, and the solvent was removed in vacuo. The residue was purified on silica gel using neat ethyl acetate as the eluant to give 400 mg (35% yield) of pure product 10a (FIG. 7). 1H NMR: 1.37 (s, 9H), 2.43 (t, 2H, J=6.4 Hz), 3.40 (t, 2H, J=6.4 Hz), 3.53-3.61 (m, 12H), 3.64 (t, 2H, J=6.4 Hz), 3.74 (t, 2H, J=6.4 Hz). 13C NMR: 27.90, 30.13, 36.06, 66.68, 70.17, 70.31, 70.32, 70.39, 70.46, 70.99, 80.22, 170.65. at 0° C. the organics were extracted into methylene chloride (3×25 mL) The combined organic layers were washed with sodium bicarbonate (25 mL) dried over magnesium sulfate the solvent was removed in vacuo The residue was purified on silica gel using neat ethyl acetate as the eluant