Boron tribromide → 3-bromo-4-chloro-N-(2-hydroxy-phenyl)-N-methyl-benzamide
反応式
[Br:1][C:2]1[CH:3]=[C:4]([CH:17]=[CH:18][C:19]=1[Cl:20])[C:5]([N:7]([C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[O:15]C)[CH3:8])=[O:6].B(Br)(Br)Br>C(Cl)Cl>[Br:1][C:2]1[CH:3]=[C:4]([CH:17]=[CH:18][C:19]=1[Cl:20])[C:5]([N:7]([C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=1[OH:15])[CH3:8])=[O:6]参加物
4
実験手順
To a cooled solution (−70° C.) of 3-bromo-4-chloro-N-(2-methoxy-phenyl)-N-methyl-benzamide (2 g, 5.64 mmol) in DCM (20 mL), BBr3 (1.7 mL, 18 mmol) was added drop-wise over a 20 minute period. The reaction temperature was allowed to increase to room temperature over 12 hrs until completion of the reaction. After concentration in vacuo the mixture was partitioned between DCM and water. 1N NaOH was added to increase pH to −5. The organic layer was separated and washed with brine and dried over Na2SO4. Concentration and purification by silica gel column chromatography eluting with hexane/ethyl acetate (4/1 with gradient up to 3/2) yielded 3-bromo-4-chloro-N-(2-hydroxy-phenyl)-N-methyl-benzamide (1.78 g, 93%). MS [M+H]+: 341.9; tR=2.56 min. (method 1)