C(C1COC(=O)N1[C:14](=[O:32])[CH:15]([CH2:25][CH:26]1[CH2:31][CH2:30][CH2:29][CH2:28][CH2:27]1)[CH2:16][C:17]([N:19]1[CH2:24][CH2:23][O:22][CH2:21][CH2:20]1)=[O:18])C1C=CC=CC=1.[OH:33]O.[Li+].[OH-]>C1COCC1.O>[CH:26]1([CH2:25][CH:15]([CH2:16][C:17]([N:19]2[CH2:20][CH2:21][O:22][CH2:23][CH2:24]2)=[O:18])[C:14]([OH:32])=[O:33])[CH2:27][CH2:28][CH2:29][CH2:30][CH2:31]1A 0.05 M solution of 1-(4-benzyl-2-oxo-oxazolidin-3-yl)-2-cyclohexylmethyl-4-morpholin-4-yl-butane-1,4-dione (1 g) in 3:1 −THF/H2O was treated at 0° C. with 8 equivalents of 30% H2O2 followed by 2.0 equivalents of LiOH. The resulting mixture was stirred at 0–25° C. until the substrate had been consumed (approximately 1 hour). The excess peroxide was quenched at 0° C. with a 10% excess of 1.5 N aqueous Na2SO3. After buffering to pH 9–10 with aqueous NaHCO3 and evaporation of the THF, the oxazolidone chiral auxiliary was recovered by MeCl2 extraction. The carboxylic acid was isolated by EtOAc extraction of the acidified (pH 1–2) aqueous phase, then recrystallized from EtOAc and hexane to yield 0.58 g of 2-cyclohexylmethyl-4-morpholin-4-yl-4-oxo-butyric acid;
Loading…
