p-Toluidine → Methyl 5-tert-butyl-3-(3-p-tolylureido)furan-2-carboxylate

Participants

Reaction Steps

The 2-carbomethoxy-5-tert-butyl-3-furyl isocyanate prepared in Step 3 was dissolved in anh. toluene (40 mL), p-toluidine (2.05 g, 6.02 mmol, 1.0 equiv) was added, and the resulting solution was stirred at room temp. for 1 h. The toluene mixture was concentrated under reduced pressure, then diluted with CHCl3 (150 mL). The organic solution was washed with a 1N HCl solution (2×100 mL) and a saturated NaCl solution (100 mL), dried (Na2SO4) and concentrated under reduced pressure. The residue was purified by flash chromatography (100 g SiO2, gradient from hexane to 10% EtOAc/hexane) to give N-(2-carbomethoxy-5-tert-butyl-3-furyl)-N′-(4-methylphenyl)urea as a yellow solid (0.71 g, 35): mp 78-9° C.; TLC (20% EtOAc/hexane) Rf0.46; 1H NMR δ1.28 (s, 9H), 2.33 (s, 3H), 3.80 (s, 3H), 7.03 (s, 1H), 7.10 (br s, 1H), 7.15 (d, J=8.5 Hz, 2H), 7.27 (d, J=8.5 Hz, 2H) 8.60 (brs, 1H); 13C NMR δ20.8, 28.5 (3C), 33.2, 51.3, 100.3, 121.7 (br s, 2C), 126.2, 129.8 (br s, 2C), 134.3 (br s), 135.0, 137.5 (br s), 152.6, 160.8, 168.5; FAB-LRMS m/z (rel abundance) 331 (M+H, 64%).

Provenance & Evidence