Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

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반응 단계

A mixture of 3.68 g (0.01 mol) of 7-β-galactosylcoumarin-3-carboxylic acid, supra, 2.30 g (0.02 mol) of N-hydroxy-succinimide, and 2.27 g (0.011 mol) of dicyclohexylcarbodiimide in 25 ml of dimethylformamide (DMF) was stirred under argon at room temperature for 1 hour. A thick precipitate of dicyclohexylurea formed and was removed by filtration. The clear filtrate was combined with 2.52 grams (g) of the hydrochloride salt of N-(tert-butyloxycarbonyl)-1,6-hexanediamine [Stahl et al, J. Org. Chem. 43:2285(1976)]. The solution was cooled to 0° C. and 2.8 ml (2.02 g, 0.02 mol) of triethylamine was added. The reaction was allowed to stir at room temperature for 2 hours, then filtered to remove the precipitate of triethylamine hydrochloride. Evaporation of the DMF under reduced pressure gave an oily residue that was stirred for 15 minutes with 100 ml of 2 N hydrochloric acid. The heavy precipitate that formed was filtered, washed with water, and dried.

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