2,4-Dimethylbenzoic acid → 3-bromo-2,4-dimethylbenzoic acid
反応式
[CH3:1][C:2]1[CH:10]=[C:9]([CH3:11])[CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].C1C(=O)N([Br:19])C(=O)C1>C(O)(C(F)(F)F)=O>[Br:19][C:10]1[C:2]([CH3:1])=[C:3]([CH:7]=[CH:8][C:9]=1[CH3:11])[C:4]([OH:6])=[O:5]参加物
4
反応条件
- 温度
- 50 °C
実験手順
2,4-Dimethylbenzoic acid (7.00 g, 46.6 mmol) and NBS (12.4 g, 69.9 mmol) were dissolved in TFA (150 mL). The mixture was then heated at 50° C. for overnight. Analysis by LC as well as TLC (hexanes/EtOAc=1/1) indicated that reaction had gone to completion. The solvent was removed in vacuo and the resulting residue was dissolved in DCM, absorbed onto silica gel, and loaded onto a silica MPLC column for separation. The desired product was separated using the solvent system of hexanes/EtOAc (1/1) to yield 3-bromo-2,4-dimethylbenzoic acid. The undesired isomeric 5-bromo-2,4-dimethylbenzoic acid was also isolated. 1H-NMR (CDCl3, 500 MHz), δ 7.868 (d, J=7.5 Hz, 1H), 7.2 (d, J=7.5 Hz, 1H), 2.793 (s, 3H), 2.526 (s, 3H).