[C:1]1([O:7][C:8](=[O:18])[NH:9][C:10]2[CH:14]=[C:13]([CH:15]3[CH2:17][CH2:16]3)[O:12][N:11]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.[Li+].[CH3:20]CC[CH2-].C(=O)=O.CC(C)=O.CI>C1COCC1>[C:1]1([O:7][C:8](=[O:18])[NH:9][C:10]2[C:14]([CH3:20])=[C:13]([CH:15]3[CH2:17][CH2:16]3)[O:12][N:11]=2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1
(5-Cyclopropyl-isoxazol-3-yl)-carbamic acid phenyl ester (0.368 g, 1.51 mmol) is dissolved in THF (10 mL) and cooled to −78° C. and flushed with nitrogen. N-butyllithium (2.17 mL, 3.47 mmol) is then added. The mixture is stirred in the dry ice/acetone bath for 30 minutes. Methyl iodide (0.10 mL, 1.66 mmol) is added neat and the reaction is stirred for 2 hours at −78° C. The reaction is quenched (0° C.) with 20 mL of a saturated solution of ammonium chloride, diluted with ethyl acetate and the organic layer is removed, dried (sodium sulfate) and concentrated to an oil that is purified via FCC (0-40% ethyl acetate:heptanes) to give the title compound as an oil. MS (ESI) m/z 259.20 (M+1).
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