Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

Participants

Reaction Steps

To a stirred solution of 6-(2-propenylhydrazone)nicotinamido-3-propanol (190 mg, 0.8 mmol) and 2-carboxyethyl-2-pyridyldisulphide (163 mg, 1.0 equiv) in THF (10 ml) at 0° C. was added dicyclohexyl-carbodiimide (157 mg, 1.0 equiv) and the mixture was stirred at 0°-5° C. for 72 hours during which time a white solid precipitated. The white solid was filtered off and the filtrate evaporated under reduced pressure. The residue was dissolved in ethyl acetate and cooled, which gave a further precipitate of dicyclohexyl urea ("DCU"). This procedure was repeated once again until all of the urea had been removed. The desired product was purified by column chromatography on silica gel using 5% methanol in dichloromethane as eluent. Re-crystallisation in ethyl acetate/ether gave white solid (85 mg, 25%). 1H NMR (CDCl3) δ1.15 (t, 3H, J=7.5 Hz), 1.95 (pentet, 2H, J=6.0 Hz), 2.36 (dq, 2H, J=5.0, 7.6 Hz), 2.80 (t, 2H, J=7.0 Hz), 3.07 (t, 2H, J=7.0 Hz), 3.50 (m, 2H), 4.04 (t, 2H, J=6.0 Hz), 6.51 (broad triplet, 1H, D2O exchangeable), 7.07-7.12 (m, 1H, 7.17-7.21 (m, 2H), 7.60-7.72 (m, 2H), 7.95-7.99 (dd, 1H, J=8.8, 2.4 Hz), 8.22 (broad s, 1H, D2O exchangeable), 8.42-8.45 (m, 1H), 8.55 (d, 1H, J{32 2.4 Hz); mass spectrum (FAB); m/e relative intensity); 448 (100, M+1), 176 (45).

Provenance & Evidence