反应详情

A solution of the ester (50)(10.00 g, 33.4 mmol) in methanol (100 mL) was added dropwise to a stirring solution of 1M NaOH (100 mL) and H2O (50 mL). TLC (1:10:100 Acetic acid: MeOH: CHCl3) after 16 hours revealed the complete loss of starting material. The solution was acidified to pH1 with conc. HCl. The resulting yellow precipitate was collected by vacuum filtration to provide the product (51) as a yellow solid (8.58 g, 90%). MP=172-175° C. 1H NMR (250 MHz, CDCl3) δ 7.71 (s, 1H), 7.40 (s, 1H), 4.99 (s, 2H), 4.13 (t, J=6.3 Hz, 2H), 3.98 (s, 3H), 2.52 (t, J=7.1 Hz, 2H), 2.15 (pent, J=6.7 Hz, 2H). 13C NMR (67.8 MHz, CDCl3) 174.5 (C12), 154.2 (Cquat.), 146.4 (Cquat.), 138.5 (Cquat.), 134.7 (Cquat.), 109.8 (C6), 109.3 (C3), 68.3 (C9), 60.9 (C1), 56.2 (C8), 30.2 (C11), 24.3 (C10). IR (cm−1) 3533, 2976, 2634, 1709, 1617, 1577, 1520, 1411, 1286, 1214, 1019, 990, 888, 876, 814, 756, 677. MS (M+ —OH) 268.0. Anal. Calcd for C12H15NO7: C, 50.53; H, 5.30; N, 4.91. Found: C, 50.48; H, 5.22; N, 4.88.

1. filtrationThe resulting yellow precipitate was collected by vacuum filtration