4-Methylmorpholine → tert-butyl (S)-3-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-4-oxo-4-(piperidin-1-yl)butanoate

Participants

Reaction Steps

(S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-4-(tert-butoxy)-4-oxobutanoic acid (Compound SP404, Fmoc-Asp(OtBu)-OH) (30 g, 72.9 mmol) was dissolved in DMF (243 mL). N-methylmorpholine (9.6 ml, 87 mmol) and then O-(7-aza-1H-benzotriazol-1-yl)-N,N,N,N-tetramethyluronium hexafluorophosphate (HATU) (33.3 g, 87 mmol) were added at 0° C., and the mixture was stirred for 10 minutes. Piperidine (7.1 ml, 71.5 mmol) was further added dropwise, and the mixture was stirred for 30 minutes. The reaction mixture was diluted with hexane/ethyl acetate=1/1 (1500 ml), and the organic layer was sequentially washed with a saturated aqueous ammonium chloride solution, a saturated aqueous sodium bicarbonate solution, water and brine. The organic extract was dried over sodium sulfate and then concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (hexane/ethyl acetate=2/1) to afford tert-butyl (S)-3-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-4-oxo-4-(piperidin-1-yl)butanoate (Compound SP403) (35.2 g, 99%).

Provenance & Evidence