Potassium Iodide → HCID 11555972, compound

Participants

Reaction Steps

Ethyl 4-[(5-{[(2S,4R)-4-[acetyl(4-chlorophenyl)amino]-2-methyl-3,4-dihydroquinolin-1(2H)-yl]carbonyl}isoxazol-3-yl)oxy]-2,2-dimethylbutanoate was prepared following the procedure for N-(4-chlorophenyl)-N-{(2S,4R)-1-[(1-isopropyl-1H-pyrazol-4-yl)carbonyl]-2-methyl-1,2,3,4-tetrahydroquinolin-4-yl}acetamide, substituting ethyl 4-{[5-(chlorocarbonyl)isoxazol-3-yl]oxy}-2,2-dimethylbutanoate for 1-isopropyl-1H-pyrazole-4-carbonyl chloride. (Ethyl 4-{[5-(chlorocarbonyl)isoxazol-3-yl]oxy}-2,2-dimethylbutanoate was prepared in three steps from methyl 3-hydroxy 5-isoxazole carboxylate. Methyl 3-hydroxy 5-isoxazole carboxylate (1.00 g, 6.94 mmol) was alkylated using ethyl 4-bromo-2,2-dimethylbutanoate (1.59 g, 7.63 mmol) in the presence of potassium carbonate (1.05 g, 7.64 mmol) and catalytic potassium iodide in DMF (5.00 mL) at room temperature overnight. Water was added to the reaction mixture and the mixture was extracted with ethyl acetate. The organics were washed with brine, dried over anhydrous sodium sulfate, filtered, concentrated in vacuo and purified on silica gel by flash chromatography using hexane/ethyl acetate (10-50% gradient) to afford methyl 3-(4-ethoxy-3,3-dimethyl-4-oxobutoxy)isoxazole-5-carboxylate in 35% yield. Selective hydrolysis of the methyl ester by subsequent treatment with lithium hydroxide (aq) (1.50 equiv.) in methanol at room temperature afforded 3-(4-ethoxy-3,3-dimethyl-4-oxobutoxy)isoxazole-5-carboxylic acid which was then treated with oxalyl chloride and catalytic DMF in dichloromethane to yield the desired ethyl 4-{[5-(chlorocarbonyl)isoxazol-3-yl]oxy}-2,2-dimethylbutanoate).

Provenance & Evidence