1,1'-Carbonyldiimidazole → (S)-6-(4-Benzoyl-benzoylamino)-2-carbazol-9-yl-hexanoic acid methyl ester

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Reaction Steps

Carbonyldiimidazole (0.162 g, 1.0 mmol) was added to a solution of 4-benzoyl benzoic acid (0.226 g, 1.0 mmol) in dry THF (10 mL) under nitrogen atmosphere at room temperature and the resulting mixture was stirred for 1 h at the same conditions. Then, (S)-methyl 6-amino-2-carbazol-9-yl-hexanoate 4 (0.310 g, 1.0 mmol) in dry THF (5 mL) was added dropwise by syringe into the reaction mixture. The reaction mixture was allowed to stir for additional 3 h at room temperature. After completion of the reaction (monitored by TLC), the solvent was removed under reduced pressure and the crude product was dissolved in ethyl acetate (50 mL) washed with brine (20 mL×2), and finally dried over anhydrous Na2SO4. Filtration followed by removal of the solvent under reduced pressure provided a gummy colorless residue, which was purified by column chromatography over silica gel using dichloromethane:methanol (98:2) as eluent to afford (S)-6-(4-benzoyl-benzoylamino)-2-carbazol-9-yl-hexanoic acid methyl ester 6 (0.290 g, 56%) as a white solid.

Provenance & Evidence