Boron tribromide → Methyl 4-hydroxybenzo[d]thiazole-6-carboxylate

HRID 1643821Notes

Reaction equation

C[O:2][C:3]1[C:8]2[N:9]=[CH:10][S:11][C:7]=2[CH:6]=[C:5]([C:12]([O:14][CH3:15])=[O:13])[CH:4]=1.B(Br)(Br)Br>C(Cl)Cl>[OH:2][C:3]1[C:8]2[N:9]=[CH:10][S:11][C:7]=2[CH:6]=[C:5]([C:12]([O:14][CH3:15])=[O:13])[CH:4]=1

Participants

Conditions

Temperature: -78 °C

Procedure

To a stirred solution of methyl 4-methoxy-1,3-benzothiazole-6-carboxylate (20.0 g, 0.0897 mol) in anhydrous CH2Cl2 (300 mL) was added drop wise BBr3 (112.5 g, 0.448 mol) at -78° C. Then the resulting mixture was stirred at −78° C. for 3 hours and allowed to warm to room temperature overnight. TLC (EtOAc/Petroleum ether 1:4) showed the reaction was complete. The reaction mixture was concentrated in vacuum and methanol (100 mL) was added drop wise to the residue. Then the mixture was concentrated again in vacuum. The residue was washed with water and recrystallized from methanol to afford the desired product (12 g, 64%) as a white solid. 1H NMR (400 MHz, CDCl3): δ 10.671 (s, 1H), 9.437 (s, 1H), 8.252-8.248 (s, 1H), 7.488-7.484 (s, 1H), 3.898 (s, 3H).

Workup

temperatureto warm to room temperature overnight
concentrationThe reaction mixture was concentrated in vacuum and methanol (100 mL)
additionwas added drop wise to the residue
concentrationThen the mixture was concentrated again in vacuum
washThe residue was washed with water
customrecrystallized from methanol

Sources & evidence

ORD record: ord-7413463013364b42892af580a65a52cf
Source dataset: uspto-grants-2012_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08119624B2

Reaction notes

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