Ethanol → 7-Bromo-5-fluoro-1-benzofuran
反応式
[Br:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[O:9][CH2:10][CH:11](OCC)OCC.C(O)C>ClC1C=CC=CC=1>[Br:1][C:2]1[C:3]2[O:9][CH:10]=[CH:11][C:4]=2[CH:5]=[C:6]([F:8])[CH:7]=1参加物
4
実験手順
2-Bromo-1-(2,2-diethoxy-ethoxy)-4-fluoro-benzene (60 g, 0.22 mol, Step A) was combined with Amberlyst-15 (20 g, Aldrich) in chlorobenzene (500 mL, Aldrich) and stirred with a paddle stirrer while the temperature was maintained at very gentle reflux. At the same time an azeotrope containing ethanol and chlorobenzene was removed via downward distillation. After 2 hours, more chlorobenzene was added (200 mL) and additional azeotrope was collected. The content of the flask was filtered and excess chlorobenzene was distilled (45° C., at ˜1 mm). The residue was purified by silica gel chromatography (5–10% ethyl ether/hexane) to give 7-bromo-5-fluoro-benzofuran (14 g, ˜33%) and taken to the next step. H1NMR (300 MHz, DMSOd6), ppm: 8.20 (d), 1H, 7.52 (m), 2H, 7.10 (d), 1H.