Boron tribromide → 7-Bromomethyl-2-(3-hydroxyphenyl)-benzoxazole
Reaction equation
B(Br)(Br)[Br:2].C[O:6][C:7]1[CH:8]=[C:9]([C:13]2[O:14][C:15]3[C:21]([CH2:22]O)=[CH:20][CH:19]=[CH:18][C:16]=3[N:17]=2)[CH:10]=[CH:11][CH:12]=1>C(Cl)Cl>[Br:2][CH2:22][C:21]1[C:15]2[O:14][C:13]([C:9]3[CH:10]=[CH:11][CH:12]=[C:7]([OH:6])[CH:8]=3)=[N:17][C:16]=2[CH:18]=[CH:19][CH:20]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
A solution of boron tribromide in methylene chloride (1.0 M; 7 ml, 7 mmol) was added dropwise to a suspension of [2-(3-methoxyphenyl)-benzoxazol-7-yl]methanol (457 mg, 1.79 mmol) in methylene chloride (10 ml) at −78° C., and the mixture was stirred at the same temperature for 1 hr. After the removal of the cooling bath, the mixture was stirred at room temperature for 2.5 hrs. The reaction mixture was poured into ice-water (50 ml), and the organic layer was separated. The aqueous layer was extracted with ethyl acetate. The organic layers were combined and dried, and the solvent was distilled off under reduced pressure. The residue was purified by flash column chromatography on silica gel (n-hexane/ethyl acetate=3−1) to give 7-bromomethyl-2-(3-hydroxyphenyl)-benzoxazole (535 mg, 98%) as a brown solid.