反应详情

To a stirred suspension of γ-tert-butyl-L-glutamic acid (4.06 g, 20.0 mmol) and cyclooctanone (3.15 g, 25 mmol) in N,N-dimethylformamide/acetic acid (99:1, v/v, 50 mL) was added sodium triacetoxyborohydride (6.36 g, 30.0 mmol) in small portions and the mixture was stirred overnight. After evaporation of the solvent, the residue was dissolved in water (50 mL). The pH was adjusted to 9 with 2 N sodium hydroxide solution, followed by extraction with diethylether (50 mL). Subsequently, the pH of the aqueous layer was carefully adjusted to 2.5 using 1.0 N hydrochloric acid. Extraction with dichloromethane afforded an organic layer, which was dried (magnesium sulphate) and concentrated under reduced pressure, yielding 4.82 g (77%) of the title compound as a white solid. ESI-MS: 314.2 (M+H)+, 336.2 (M+Na)+. Rf (silica gel; ethyl acetate/pyridine/acetic acid/water 63:20:6:11, v/v): 0.80.

1. customAfter evaporation of the solvent
2. dissolutionthe residue was dissolved in water (50 mL)
3. extractionfollowed by extraction with diethylether (50 mL)
4. extractionExtraction with dichloromethane
5. customafforded an organic layer, which
6. dry with materialwas dried (magnesium sulphate)
7. concentrationconcentrated under reduced pressure