Reaction Steps
4-Chlorobenzoyl chloride (1.10 mL, 8.57 mmol) is added slowly to a solution of ethyl hydroxycarbamate 6 (1.00 g, 9.52 mmol) and triethylamine (1.19 mL, 8.57 mmol) in diethyl ether (30 mL) at 0° C. then stirred at room temperature for 30 min. The reaction is quenched with HCl (1 M; 10 mL) then water (100 mL) is added and extracted with diethyl ether (100 mL). The organic layer is washed with sat. NaHCO3 (50 mL), water (50 mL), dried with MgSO4 and concentrated. The residue is purified by flash column chromatography (silica gel, petroleum ether/ethyl acetate 9:1 then 8:2) to yield 7 (1.54 g) as an off-white solid. M.p. 79° C. (determined by differential scanning calorimetry, sharp onset); FTIR (neat, cm−1) 3210, 3094, 2990, 1765, 1708, 1588, 1495, 1487, 1473, 1443, 1401, 1368, 1298, 1283, 1249, 1235, 1177, 1121, 1107, 1090, 1054, 1016, 996, 876, 852, 771, 747, 728, 681; 1H NMR (500 MHz, CDCl3) δ 8.34 (s, 1H), 8.02 (dt, J=2.1, 8.7 Hz, 2H), 7.46 (dt, J=2.1, 8.7 Hz, 2H), 4.28 (q, J=7.1 Hz, 2H), 1.31 (t, J=7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 165.1, 156.6, 140.9, 131.3, 129.1, 125.2, 63.0, 14.3; HRMS (ES+) m/z calcd for C10H10ClNO4 (M+Na)+ 266.0191, found 266.0199.
