Dimethylformamide → N,N'-Dicyclohexylurea

Participants

Reaction Conditions

Reaction Steps

An equimolecular mixture (10-2M) of L-N-Boc-NG -nitroarginine and N-B-hydroxyethyl morpholine is dissolved in 30 ml of anhydrous dimethyl formamide (DMF), then 3×10-3M of dimethylaminopyridine (DMAP) is added. The solution is cooled to 0 degrees C. and 10-2M of dicyclohexyl carbodiimide (DDC) is added. It is stirred at 0 degrees C. for 10 minutes, then the stirring is continued at room temperature for 24 hours. The precipitate of dicyclohexyl urea formed is filtered and the solvent eliminated. The residue is recovered by ethyl acetate, then washed once with water and once with saturated NaCl. The elimination of the solvent leaves a viscous product which is chromatographed on a silica column (eluant CHCl3/MeOH9595 then 90:10); the compound (4) is obtained in the form of an oil which crystalizes.

Provenance & Evidence