[C:1]([NH:8][C@H:9]([C:19](O)=[O:20])[CH2:10][O:11][CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].CN1CCOCC1.C(OC(Cl)=O)C(C)C.[BH4-].[Na+].C(=O)(O)[O-].[Na+]>C(COC)OC.O>[CH2:12]([O:11][CH2:10][C@@H:9]([NH:8][C:1]([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2])[CH2:19][OH:20])[C:13]1[CH:14]=[CH:15][CH:16]=[CH:17][CH:18]=1N-BOC-O-benzylserine (5.0 g, 16.9 mmol) in 30 mL dimethoxyethane was treated with 4-methylmorpholine (2.0 mL, 18.6 mmol) and cooled to 0° C. The solution was treated with isobutylchloroformate (2.3 mL, 17.8 mmol) and the resulting suspension stirred for 15 minutes, then filtered. The solids collected were washed with 2 portions of dimethoxyethane and the washings combined with the original filtrate. This material was cooled in an ice bath and treated with a cold solution of sodium borohydride (1.93 g, 50.8 mmol) in 40 mL 1/2 saturated sodium bicarbonate and the reaction stirred for 2 hours. The mixture was diluted with water and extracted with 3 portions of ethyl acetate. The combined organic extracts were washed with saturated aqueous sodium bicarbonate, water and brine, dried, filtered and concentrated to provide the title compound. MS (DCI, NH3): 282 (MH+); 299 (M+NH4)+.
Loading…
