[CH3:1][C:2]([O:5][CH2:6][CH:7]=[N:8][OH:9])([CH3:4])[CH3:3].ClN1C(=O)CCC1=O.[CH:18]1([C:22](=O)[CH2:23][C:24]([O:26][CH2:27][CH3:28])=[O:25])[CH2:21][CH2:20][CH2:19]1.[O-]CC.[Na+]>CN(C)C=O.O1CCCC1>[CH:18]1([C:22]2[O:9][N:8]=[C:7]([CH2:6][O:5][C:2]([CH3:4])([CH3:3])[CH3:1])[C:23]=2[C:24]([O:26][CH2:27][CH3:28])=[O:25])[CH2:19][CH2:20][CH2:21]1To a solution of (1,1-dimethylethyl)oxyethanal oxime (1.71 g, 13.0 mmol) in N,N-dimethylformamide (10 mL) was added N-chlorosuccinimide (1.74 g, 13.0 mmol) while the flask was in a water bath. After approximately 10 minutes the flask was removed from the water bath and the solution was stirred for approximately 1 hour. The solution, containing the crude imidoyl chloride, was then poured into ether and washed twice with water followed by brine, and then was dried over magnesium sulfate and concentrated. Then to a separate solution of ethyl 3-cyclobutyl-3-oxopropanoate (2.66 g, 15.6 mmol) in tetrahydrofuran (8 mL) at 0° C. was added sodium ethoxide (21 wt % solution in ethanol, 5.82 mL, 15.6 mmol). The above imidoyl chloride was diluted with tetrahydrofuran (6 mL) then added to the solution containing the ketoester. A solid was seen to precipitate. After the addition the solution was allowed to warm to ambient temperature and stirred overnight. The mixture was then poured into ether and washed twice with water followed by brine, dried over magnesium sulfate and concentrated to afford ethyl 5-cyclobutyl-3-{[(1,1-dimethylethyl)oxy]methyl}-4-isoxazolecarboxylate (3.13 g, 87%). 1H-NMR (400 MHz, DMSO-d6) δ 4.53 (s, 2H), 4.22 (q, J=7 Hz, 2H), 4.17-4.05 (m, 1H), 2.33-2.27 (m, 4H), 2.09-2.03 (m, 1H), 1.95-1.86 (m, 1H), 1.26 (t, J=7 Hz, 3H), 1.17 (s, 9H).
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