Dimethylformamide → N,N'-Dicyclohexylurea

Participants

Reaction Steps

Suspended in 200 ml of acetonitrile are N-(9-fluorenylmethoxycarbonyl)-4-L-hydroxyproline (20.5 g, 50 mmol), followed by the addition of 12 ml of N, N'-dimethylformamide under ice cooling. The resulting mixture is stirred, to which 11.9 g (1.1 equivalents) of pentafluorophenol and 13.2 g (1.1 equivalents) of dicyclohexylcarbodiimide are added. The resulting suspension is stirred for one hour and then, stirred overnight at room temperature. Dicyclohexylurea produced by the reaction is removed by filtration and the filtrate is concentrated. The concentrate is dissolved in ethyl acetate. Dicyclohexylurea, which remained undissolved, is removed by filtration. The operations of dissolution in ethyl acetate, filtration, and concentration are additionally repeated twice. N,N'-Dimethylformamide contained in the concentrate is completely distilled off under reduced pressure. The concentrate is dissolved in ethyl acetate, and to the resulting solution is added n-hexane for re-precipitation, whereby 28.0 g of the product is obtained (yield: 93%).

Provenance & Evidence