Sodium Chloride → [(S)-3-(9H-fluoren-9-ylmethoxycarbonylamino)-4-morpholin-4-yl-4-oxobutyl]carbamic acid tert-butyl ester

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Reaction Steps

(S)-4-tert-Butoxycarbonylamino-2-(9H-fluoren-9-ylmethoxycarbonylamino)butyric acid (150 mg, 0.341 mmol) was dissolved in N,N-dimethylformamide (1.0 ml), and then 2-3H-1,2,3-triazolo[4,5-b]pyridin-3-ol (51 mg, 0.377 mmol), O-(7-azabenzotriazole-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (148 mg, 0.377 mmol),2,4,6-trimethylpyridine (91 μl), and morpholine (45 μl, 0.512 mol) were added thereto at room temperature. After the mixture was stirred at room temperature for 16 hours, a saturated aqueous sodium chloride solution (20 ml) was added to stop the reaction. The mixture was extracted three times with ethyl acetate (20 ml). The ethyl acetate extraction solutions were combined together, and sequentially washed with a saturated aqueous sodium bicarbonate solution (20 ml) and a saturated aqueous sodium chloride solution (20 ml). The washed ethyl acetate solution was dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography (developing solvent: n-hexane:ethyl acetate=1:1) to yield [(S)-3-(9H-fluoren-9-ylmethoxycarbonylamino)-4-morpholin-4-yl-4-oxobutyl]carbamic acid tert-butyl ester (172.2 mg) as a white amorphous material.

Provenance & Evidence