98% |
With sodium hydrogencarbonate; In 1,4-dioxane; water; at 0℃; for 2.5h; |
A solution of (2S, 4R) -methyl 4-hydroxypyrrolidine-2-carboxylate hydrochloride (5.5 g, 30 mmol) in 1, 4-dioxane (17 mL) was cooled to 0 , and then a solution of sodium carbonate (3.5 g, 33 mmol) in H 2O (17 mL) was added in portions, after that, CbzCl (4.8 mL, 34 mmol) was added over 30 min. The obtaining reaction mixture was stirred at 0 for 2 hours. The mixture was concentrated in vacuo to remove 1, 4-dioxane, the residue was extracted with ethyl acetate (3 x 100 mL) . The combined organic phases were dried over anhydrous sodium sulfate, filtered and the filtrate was concentrated in vacuo. The residue was purified by silica gel chromatograph (PE/EtOAc (V/V) = 1/1) to give the title compound as a colorless oil (6.7 g, 79%) . |
98% |
With sodium hydrogencarbonate; In 1,4-dioxane; water; at 0℃; for 2.5h; |
<strong>[114676-59-4](2R,4R)-4-hydroxypyrrolidine-2-carboxylic acid methyl ester hydrochloride</strong> (8 g, 44.0 mmol), 1,4-dioxane(80mL), water (80mL),Sodium bicarbonate (7.4 g, 88 mmol) andBenzyl chloroformate (8.0 mL, 53 mmol) was used as a raw material.According to the method of step 1 of embodiment 1,The title compound was obtained as a colorless oil (12.1 g, yield: 98%).(2S,4R)-4-Hydroxypyrrole-2-carboxylic acid methyl ester hydrochloride (5.5 g, 30 mmol) The 1,4-dioxane (17 mL) solution was cooled to 0 C. Then sodium carbonate (3.5 g, 33 mmol) was added in portions. H2O (17mL) solution, Then add CbzCl (4.8 mL, 34 mmol), After 30 minutes, the drop is completed. The resulting reaction solution was stirred at 0 C for 2 hours. The reaction mixture was concentrated to dryness The residue was purified with EtOAc EtOAc m. The title compound was obtained as a colorless oil ( 6.7 g, yield: 79%). |
7.4 g |
With sodium carbonate; In tetrahydrofuran; water; at 0 - 20℃; for 2h; |
To a solution of D (17.94 g, 98.8 mmol) and Na2C03 (10.5 g, 98.8 mmol) in THF/H20 (150 mL/50 mL) was added CbzCI (20.2 g, 1 18.56 mmol) at 0 C and the mixture was stirred at room temperature for 2 h. The mixture was filtered through filter paper and the filtrate was concentrated. Water (200 mL) was added and the product was extracted with EtOAc (100 ml x 3). The combined organic layers were washed with brine, dried (MgS0 ), filtered, and concentrated. The residue was purified by column chromatography (silica gel, PetEther/EtOAc=5/1 -2/1) to get the desired product (7.4 g, 27%) as a light yellow oil. LC-MS : 279.9 ([M+1]+ ). |