[CH3:1][C:2]1[S:3][C:4]([C:8]([OH:10])=[O:9])=[C:5]([CH3:7])[N:6]=1.[Li+].CC([N-]C(C)C)C.[CH2:19]([C:23]1[C:27]([CH2:28]Cl)=[C:26]([CH3:30])[O:25][N:24]=1)[CH2:20][CH2:21][CH3:22]>C1COCC1>[CH2:19]([C:23]1[C:27]([CH2:28][CH2:1][C:2]2[S:3][C:4]([C:8]([OH:10])=[O:9])=[C:5]([CH3:7])[N:6]=2)=[C:26]([CH3:30])[O:25][N:24]=1)[CH2:20][CH2:21][CH3:22]To a stirred solution of 2,4-dimethyl-thiazole-5-carboxylic acid (157 mg, 1.0 mmol) in THF (3 mL) at −78° C. and under argon was added LDA (1.0 mL of a 2M solution in THF, 2.0 mmol) dropwise. After 1.5 h a solution of 3-butyl-4-chloromethyl-5-methyl-isoxazole (188 mg, 1.0 mmol) in THF (2 mL) was added dropwise. After 1 h the reaction mixture was quenched with HCl (1 N, 10 mL) then warmed to room temperature and extracted with ethyl acetate. The combined extracts were dried, filtered and concentrated. Purification by chromatography (silica, 0 to 10% methanol in dichloromethane) gave the title compound (210 mg, 68%) as an off white solid. MS: m/e=307.3 [M+H]+.
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