4-Nitrophenol → N,N'-Dicyclohexylurea

Participants

Reaction Steps

Boc-Gly-Pro-OH (2.8 g, 0.01 mol.) and p-nitrophenol (1.7 g, 0.012 mol.) were dissolved in DCM (100 ml) and DCC (2.1 g, 0.01 mol.) was added to the solution by portions while stirring the solution. A precipitate (dicyclohexylurea, DCU) soon formed. After stirring the solution at room temperature for 3.5 hours, TLC analysis (developing solvents:ethyl acetate/hexane, 3:1) showed that all the starting material Boc-Gly-Pro-OH was consumed. The Rf for the product Boc-Gly-Pro-ONp is 0.45 in this solvent system. DCU was removed by filtration and DCM was removed under reduced pressure. Ethyl acetate was added to the remaining oil and the resulting solution was chilled to 0° C. More precipitate formed and was removed by filtration. The above procedures were repeated and a brownish oil was obtained. The product was directly used in the synthesis of Boc-Gly-Pro-Hyp(OBz)--OH without further purification and characterization.

Provenance & Evidence