反应 #1435714
ord-c716211aff1d4b5286bd612d1192e9ab
反应方程式
反应条件
后处理
- 1其他The crystalline precipitate was isolated by filtration
实验过程
Diene component: To a solution of methyl octa-4,6-dienoate (16) (6 g) in methanol (10 ml) was added hydrazine (3 ml) at room temperature. After 24 h, the solution was diluted with water (50 ml). The crystalline precipitate was isolated by filtration to afford octa-4,6-dienoic acid hydrazide (17) as colorless microcrystals, yield 5.7 g. Dextran (nominal MW 10 kDa, Pharmacia) was diafiltered through a YM10 membrane (MW cutoff 10 kDa, Millipore) using 3 changes of water. The solution that passed through the membrane was diafiltered through a YM3 (MW cutoff 3000 Da) membrane, suing five changes of water. The material retained by the membrane was lyophilized. A stirred solution of the dextran 18 thus obtained (22.5 mg, 2.25 μmol, corresponding to 139 μmol of glucose) in H2O (2.2 ml) at 5° C. (ice bath) was equipped with a temperature-sensing pH electrode, and 0.1 M NaOH was added with a 100 μL microsyringe until the pH reached 10.5. To this solution was added BrCN (50 μL of a 5 M solution in acetonitrile). The pH of the solution was maintained between 10.5 and 10.8 by addition of 0.1 M NaOH with a microsyringe. After 6 min, the solution was adjusted to pH 8.5 by addition of pH 8.0 phosphate buffer (ca. 1 ml). To the reaction mixture was immediately added a solution of octa-4,6-dienoic acid hydrazide (3.5 mg, 235 μmol) in 0.5 ml dimethyl sulfoxide. The pH of the reaction mixture rose to 8.95, at a temperature of 9° C. The ice bath was removed and the stirred solution was allowed to reach 25° C. After 2.5 h, the pH was 8.18 and remained unchanged over 5 min. The solution of 20 was diafiltered through a YM-3 membrane using 5 changes of water (4 ml each).