反应详情

Phosgene (1.93M in toluene, 1.3 mL, 2.5 mmol, 10 equiv) was added rapidly to a solution of methyl 3-amino-5-tert-butylfuran-2-carboxylate (0.050 g, 0.25 mmol) and anh. pyridine (1.0 mL) in anh. toluene (5 mL) at room temp. After 30 min, the orange suspension was concentrated under reduced pressure, then successively charged with dry toluene (1 mL) and concentrated (2×). Finally, anh. toluene (3 mL) was added followed by p-toluidine (0.100 g, 0.93 mmol, 3.7 equiv). The orange mixture was stirred overnight, diluted with EtOAc, washed with a 1M HCl solution and a concentrated NaCl solution, then dried (Na2SO4) and concentrated under reduced pressure. The residue was purified by flash chromatography to give N-(2-carbomethoxy-5-tert-butyl-3-furyl)-N′-(4-methylphenyl)urea (0.080 g, 96%) as a pale yellow oil: 1H NMR (CDCl3) δ1.28 (s, 9H), 2.30 (s, 3H), 3.77 (s, 3H), 7.02 (s, 1H), 7.11 (d, J=8.1 Hz, 2H), 7.27 (d, J=8.1 Hz, 2H), 7.87 (br s, 1H), 8.68 (br s, 1H); 13C NMR (CDCl3) δ20.6, 28.3 (3C), 33.0, 51.0, 100.1, 121.4 (2C), 126.0, 129.5 (2C), 134.0, 134.8, 137.7, 152.5, 160.5, 168.2; FTIR (neat) 3400-3200 (br, m), 2966 (s), 1676 (s), 1622 (s), 1536 (s), 1306 (s), 1097 (m) cm−1.

1. concentrationthe orange suspension was concentrated under reduced pressure
2. additionsuccessively charged with dry toluene (1 mL)
3. concentrationconcentrated (2×)
4. additionFinally, anh. toluene (3 mL) was added
5. washwashed with a 1M HCl solution
6. dry with materiala concentrated NaCl solution, then dried (Na2SO4)
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified by flash chromatography