Hydrogen Bromide → 5-Bromo-2-methylbenzothiazole

HRID 402099Notes

Reaction equation

N([O-])=O.[Na+].Cl.Cl.[CH3:7][C:8]1[S:9][C:10]2[CH:16]=[CH:15][C:14](N)=[CH:13][C:11]=2[N:12]=1.O.[OH-].[NH4+].[BrH:21]>[Cu]Br>[CH3:7][C:8]1[S:9][C:10]2[CH:16]=[CH:15][C:14]([Br:21])=[CH:13][C:11]=2[N:12]=1

Participants

Conditions

Temperature: 0 °C

Procedure

Sodium nitrite (0.9 g, 13 mmol) was added portionwise to a suspension of 2-methyl-5-aminobenzothiazole dihydrochloride (2.0 g, 8 mmol) in hydrobromic acid (24 ml) at 0° C. The resulting mixture was added dropwise to a solution of copper(I) bromide (4.0 g, 14 mmol) in hydrobromic acid (50 ml) at 0° C. After stirring at 0° C. for 2 hours, water was added. The reaction mixture was basified to pH 9 using aqueous ammonium hydroxide and was extracted with ethyl acetate. The combined organic layers were dried over magnesium sulfate to give 2-methyl-5-bromobenzothiazole (1.0 g, 52%, 82% AUC GC) after chromatography (9:1 heptane/ethyl acetate): 1H NMR (300 MHz, DMSO-d6) δ 8.12 (d, J=1.8 Hz, 8.02 (dd, 1H) J=8.4, 1.5 Hz, 1H), 7.56 (dd, J=8.7, 2.1 Hz, 1H), 2.81 (s, 3H).

Workup

extractionwas extracted with ethyl acetate
dry with materialThe combined organic layers were dried over magnesium sulfate

Sources & evidence

ORD record: ord-3746329ea75a4ae38673c27b0a05bc27
Source dataset: uspto-grants-2014_06
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08741901B2

Reaction notes

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