Reaction Steps
To a solution of 18 (30 g, 107.4 mmol, 1.0 equiv) in DMF (170 mL) at room temperature was added solid K2CO3 (29.6 g, 214.2 mmol, 2.0 equiv) then allylbromide (10.2 mL, 116.3 mmol, 1.1 equiv) dropwise. The suspension was stirred at room temperature for 9 hours, after which time water (500 mL) was added and extracted with ether (4×250 mL). The organics were combined, washed with brine, dried over MgSO4, and concentrated. Purification by flash chromatography (20→60% EtOAc/hexane) afforded 19 (31.6 g, 92%) as a clear oil. Rf=0.27 (25% EtOAc/hexane); FTIR (neat, cm−1) 3343, 2919, 1721, 1510, 1239, 1215, 1176, 1052, 1017; 1H NMR (400 MHz, CDCl3) δ7.00 (d, J=8.4 Hz, 2H), 6.79 (d, J=8.8 Hz, 2H), 5.99 (m, 1H), 5.85 (m, 1H), 5.44 (d, J=8.0 Hz, 1H), 5.36 (dd, J=17.4, 1.2 Hz, 1H), 5.25 (s, 1H), 5.22 (dd, J=10.2, 1.6 Hz, 1H), 5.15 (dd, J=10.4, 1.2 Hz, 1H), 4.56 (dd, J=14.2, 6.0 Hz, 1H), 4.51 (d, J=5.6 Hz, 2H), 4.45 (d, J=5.2 Hz, 2H), 3.66 (s, 3H), 3.03 (dd, J=14.4, 5.2 Hz, 1H), 2.96 (dd, J=14.0, 6.4 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ172.0, 157.5, 155.4, 133.1, 132.5, 130.0, 127.8, 117.4, 117.3, 114.5, 68.4, 65.5, 54.7, 52.0, 37.0; MS (ES+) calculated for C17H21NO5 (M+H)+: 320.1420, found: 320.2.
