[CH:1]1([CH2:4][CH2:5][C:6]([N:8]2[C@@H:12]([CH:13]([CH3:15])[CH3:14])[CH2:11][O:10][C:9]2=[O:16])=[O:7])C[CH2:2]1.[Cl-].C(O)(=O)CCC=C.CN1CCOCC1.C([Li])CCC.CCCCCC.CC([C@H]1COC(=O)N1)C.[NH4+].[Cl-]>C1COCC1.O>[CH3:15][CH:13]([C@H:12]1[CH2:11][O:10][C:9](=[O:16])[N:8]1[C:6](=[O:7])[CH2:5][CH2:4][CH:1]=[CH2:2])[CH3:14]
3-(3-Cyclopropyl-1-oxopropyl)-4(S)-(1-methylethyl)-2-oxazolidinone: A solution of mixed anhydride was prepared by adding, under N2, pivoloyl chloride (14.8 mL, 120 mmol) over a period of 5 min to a cooled solution (0°) of 4-pentenoic acid (12.3 mL, 120 mmol) and N-methylmorpholine (15.4 mL, 140 mmol). The mixture was stirred at 0° for 30 min. Meanwhile, a second solution was prepared by adding dropwise under N2 a 1.4M solution of butyllithium in hexane (71 mL, 100 mmol) to a stirred cooled solution (-78°) of (S)-4-(1-methylethyl)-2-oxazolidinone (12.9 g, 100 mmol) in dry THF (300 mL) over a period of 45 min. (Note: The agitation was done by an overhead stirrer.) After stirring for 15 min at -78°, the latter solution was added by cannulation to the stirred solution of the mixed anhydride at -78° over a period of 20 min. The mixture was stirred for an additional 30 min at the same temperature. A saturated aqueous solution of NH4Cl (50 mL) was added and the mixture was allowed to warm to room temperature. The mixture was diluted with H2O (300 mL). The organic layer was separated. The aqueous layer was extracted with EtOAc (3×). The combined organic phases were dried (Na2SO4) and evaporated to dryness under reduced pressure to give an oily residue [i.e. 4(S)-(1-methylethyl)-3-(1-oxo-4-pentenyl)-2-oxazolidinone].
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