Cesium carbonate → {7-[5-(4-Chloro-phenyl)-isoxazol-3-ylmethoxy]-benzo[b]thiophen-3-yl}-acetic acid

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Reaction Steps

Cesium carbonate (0.31 g, 90 mmol) was added to a stirred solution of compound 77B from the preceding step (0.14 g, 0.63 mmol) and commercially available 3-chloromethyl-5-(4-chloro-phenyl)-isoxazole (0.14 g, 0.63 mmol) in 15-20 mL of acetonitrile at room temp. After 20 hours the mixture was stripped of solvent in vacuo. The residue was dissolved in dichloromethane and filtered through a short column of Celite® over silica gel, eluting with several column volumes of solvent. The filtrate was stripped of solvent in vacuo, and the residue recrystallized from DMF to afford 0.1 g (38% yield) of the title compound as a snow-white solid; mp 155-156° C. Calc for C21H16ClNO4S: C, 60.94; H, 3.90; N, 3.38. found: C, 60.67; H, 3.72; N, 3.41. Step 4. Preparation of {7-[5-(4-Chloro-phenyl)-isoxazol-3-ylmethoxy]-benzo[b]thiophen-3-yl}-acetic acid (Compound 77D)

Provenance & Evidence