[C:1]([OH:7])(=O)[CH2:2][CH2:3][CH2:4][CH3:5].CCN(CC)CC.CC(C)(C)C(Cl)=O.[CH3:22][C@H:23]1[C@@H:27]([C:28]2[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=2)[O:26][C:25](=[O:34])[NH:24]1.[Li+].[Cl-]>C1COCC1>[CH3:22][C@H:23]1[C@@H:27]([C:28]2[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=2)[O:26][C:25](=[O:34])[N:24]1[C:1](=[O:7])[CH2:2][CH2:3][CH2:4][CH3:5]To a 0° C. stirred solution of valeric acid (3.83 mL, 35.2 mmol) and Et3N (14.7 mL, 106 mmol) in dry THF (175 mL) was added trimethylacetyl chloride (5.29 mL, 42.3 mmol) dropwise. The mixture was stirred at 0° C. for 1 hour and (4S,5R)-(−)-4-methyl-5-phenyl-2-oxazolidinone (7.50 g, 42.3 mmol) was added followed by LiCl (1.79 g, 42.3 mmol). The reaction was warmed to room temperature overnight with good stirring. The mixture was filtered and the filtrate was concentrated under reduced pressure. Et2O (75 mL) was added to the residue, which was washed with sat. NaHCO3 (3×40 mL), 1N HCl (3×40 mL), and brine (2×40 mL). The organic phase was dried over MgSO4, filtered and concentrated under reduced pressure to give a quantitative yield of crude product.
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