4-Methylmorpholine → (9H-fluoren-9-yl)methyl tert-butyl (4-hydroxybutane-1,3-diyl)(S)-dicarbamate

Participants

Reaction Conditions

Reaction Steps

(S)-4-tert-Butoxycarbonylamino-2-(9H-fluoren-9-ylmethoxycarbonylamino)butyric acid (493 mg, 1.12 mmol) was dissolved in tetrahydrofuran (1 ml), and then isobutyl chloroformate (0.15 ml, 1.14 mmol) and N-methylmorpholine (0.125 ml, 1.15 mmol) were added thereto at −15° C. After stirring for one hour, the precipitate was filtrated and washed with tetrahydrofuran (7 ml). The filtrate was cooled to −15° C., and an aqueous solution (4 ml) of sodium borohydride (127 mg, 3.36 mmol) was dropwise added thereto. After stirring for 30 minutes, water (25 ml) was added to the solution and extracted three times with ethyl acetate (20 ml). The 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: dichloromethane:methanol=50:1) to yield [(S)-3-(9H-fluoren-9-ylmethoxycarbonylamino)-4-hydroxybutyl]carbamic acid tert-butyl ester (411 mg) as a colorless oily material.

Provenance & Evidence