| 95% |
With triethylamine; In dichloromethane; at 20℃; for 12h;Inert atmosphere; |
Using acetic anhydride (Ac2) O as the acylating agent, the reaction time can be controlled so that the yield can reach more than 90%The specific operation is:100ml three-necked bottle, add N2 protection,<strong>[530-57-4]Syringic acid</strong>(19.8 g, 0.1 mol) was added to 100 ml of dichloromethane,30 ml (0.2 mol) of triethylamine was slowly added dropwise, and the sample was completely dissolved, and 15 ml (0.15 mol) of acetic anhydride was added dropwise,TLC to monitor the progress of the reaction, to be 12h reaction is completed,The reaction solution was concentrated to 30 ml by vacuum suction filtration,Dropping 1N concentrated hydrochloric acid to pH 5,At this time a large number of white crystals sucked out,Dried and dried to obtain crude acetosuccinic acid (22.7 g, 95%); |
| 89% |
With triethylamine; In 1,2-dichloro-ethane; at 50℃; for 5h; |
3.36 g of syringic acid and 20 mL of 1,2-dichloroethane were added to a 100 mL three-necked flask, the temperature was raised to 50 C, and a mixture of 2.8 mL of acetic anhydride and 6 mL of triethylamine was added dropwise at 50 C. After reacting for 5 hours, the reaction is completed and extracted with 5 mL of a 5% sodium chloride solution to obtain an extracted aqueous phase and a single extracted organic phase, and then the extracted organic phase is reused with 5 mL of a 5% by mass of carbonic acid. The sodium solution is extracted to obtain a second-extracted aqueous phase, and the primary extracted aqueous phase and the secondary extracted aqueous phase are combined, and then the pH is adjusted to neutral with a mass fraction of 10% hydrochloric acid, filtered and dried to obtain a white solid. 3.62 g of acetyl syringic acid, the yield was 89.0%; |
| 86.6% |
With dmap; In dichloromethane; for 20h; |
198 g (1.0 mol) of syringic acid was dispersed in 1000 mL of methylene chloride, and 97.6 g (0.8 mol) of 4-dimethylaminopyridine was added to the mixture, and the mixture was slowly added dropwise with 122.5 g (1.2 mol) of acetic anhydride20h,After drying the dichloromethane, add Into 900ml anhydrous ethanol heat dissolved, then add 600ml water stirring evenly static crystallization, filter, filter cake with 200ml water cleaning A total of 208 g of a pale brown crystalline compound (I) was dried and the yield was 240 g and the yield was 86.6%. |
| 80% |
With acetic acid; triethylamine; In dichloromethane; for 5h; |
19.8 g (0.1 mol) of syringic acid was added to 100 ml of dichloromethane,Triethylamine (30 mL, 0.2 mol) was slowly added dropwise, After the solution was clarified, 15 ml (0.15 mol) of acetic anhydride was added,After 5h,Reaction is completed,Drying the reaction solvent,Then, 1N HCL solution was added thereto,Adjust the pH of 5 or so,A large number of white crystal precipitation,1.32 g of acetochloric acid, Yield 80%. |
| 266 mg |
With pyridine; at 0℃; for 2h; |
4-Hydroxy-3,5-dimethoxybenzoic acid (300 mg, 1 .51 mmol) is dissolved in pyridine (732 pL, 9.08 mmol) at 0C. Acetic anhydride (214 pL, 2.27 mmol) is added dropwise while the mixture is stirred. The ice bath is kept for 2h, after which the mixture is pouredinto ice water. The mixture is extracted with DCM (3x), the organic phase is washed with 1 N HCI solution (3x), with water and with brine, dried over sodium sulfate, filtered and evaporated, to give 4-acetoxy-3,5-dimethoxybenzoic acid (266 mg, 1 .10 mmol). |
| 266 mg |
With pyridine; at 0℃; for 2h; |
Intermediate 14: 4-acetoxy-3,5-dimethoxybenzoic acid 4-Hydroxy-3,5-dimethoxybenzoic acid (300 mg, 1.51 mmol) is dissolved in pyridine (732 muL, 9.08 mmol) at 0C. Acetic anhydride (214 muL, 2.27 mmol) is added dropwise while the mixture is stirred. The ice bath is kept for 2h, after which the mixture is poured into ice water. The mixture is extracted with DCM (3x), the organic phase is washed with 1 N HCl solution (3x), with water and with brine, dried over sodium sulfate, filtered and evaporated, to give 4-acetoxy-3,5-dimethoxybenzoic acid (266 mg, 1.10 mmol). |
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