1,1'-Carbonyldiimidazole → Methyl3,3-dimethyl-2-(3-(methylsulfonylcarbamoyl)phenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate

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Reaction Steps

A solution of 3-(6-(methoxycarbonyl)-3,3-dimethyl-1,2,3,4-tetrahydroquinolin-2-yl)benzoic acid (150 mg, 0.44 mmol) and 1,1′-carbonyldiimidazole (214 mg, 1.32 mmol) in tetrahydrofuran (3 mL) was heated to 60° C. for 2 h, then was cooled to room temperature and treated with methanesulfonamide (54.2 mg, 0.57 mmol, 1.3 eq.). After stirring for 10 min, the reaction mixture was treated with dropwise addition of a solution of 1,8-diazabicyclo[5.4.0]undec-7-ene (221 mg, 1.45 mmol) in tetrahydrofuran (1 mL). Upon completion of addition, the resultant mixture was stirred overnight. Thin layer chromatography (petroleum ether:ethyl acetate=1:1) showed the reaction was complete. The reaction mixture was quenched with brine and acidified with 1N hydrochloric acid solution to pH=5, extracted with ethyl acetate (twice). The combined organic layers were washed with brine for 3 times, dried over anhydrous sodium sulfate. Removal of the solvent in vacuo gave 205 mg of methyl 3,3-dimethyl-2-(3-(methylsulfonylcarbamoyl)phenyl)-1,2,3,4-tetrahydroquinoline-6-carboxylate as a white solid, which was purified by column chromatography (petroleum ether: ethyl acetate=2:1 to 1:1) to afford 58 mg of white solid, which was used in next step.

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