[O:1]=[C:2]1[C@@H:9]2[C@@H:5]([CH2:6][N:7]([C:10]([O:12][C:13]([CH3:16])([CH3:15])[CH3:14])=[O:11])[CH2:8]2)[CH2:4][CH2:3]1.C1C=C[NH+]=CC=1.[Br:23][Br-]Br>O1CCCC1>[Br:23][CH:3]1[CH2:4][C@@H:5]2[CH2:6][N:7]([C:10]([O:12][C:13]([CH3:16])([CH3:15])[CH3:14])=[O:11])[CH2:8][C@@H:9]2[C:2]1=[O:1]To a solution of (3aR,6aS)-tert-butyl 4-oxohexahydrocyclopenta[c]pyrrole-2(1H)-carboxylate (4 g, 17.76 mmol), in tetrahydrofuran (30 mL) at 0° C. was added pyridinium bromide perbromide (6.62 g, 18.64 mmol). The mixture was stirred for 3 hours at room temperature, wherein an ice bath was needed to keep the mixture at about room temperature. The reaction mixture was quenched with 1 N NaHCO3 solution (80 mL) and 1 N sodium thiosulfate (20 mL). The mixture was stirred for 0.5 hours and extracted with ethyl acetate. The organic layer was separated and concentrated. The crude product was purified chromatographically using a 40 g silica gel cartridge and eluting with a gradient of 0-3% methanol/dichloromethane over 20 minutes to give (3aR,6aS)-tert-butyl 5-bromo-4-oxohexahydrocyclopenta[c]pyrrole-2(1H)-carboxylate: MS (ESI+) m/z 321 (M+NH4)+.
Wird geladen…