Benzothiazole, 2,5-dimethyl- → 4-Bromo-2,5-dimethyl-1,3-benzothiazole

HRID 1192463Notes

Reaction equation

HRID 1192463 reaction equation
[CH3:1][C:2]1[S:3][C:4]2[CH:10]=[CH:9][C:8]([CH3:11])=[CH:7][C:5]=2[N:6]=1.[Br:12]Br>C(Cl)(Cl)Cl>[Br:12][C:7]1[C:5]2[N:6]=[C:2]([CH3:1])[S:3][C:4]=2[CH:10]=[CH:9][C:8]=1[CH3:11]

Participants

4

Reactant 2

HCID 7227Benzothiazole, 2,5-dimethyl-HCID 24408Bromine

Product 1

HCID 672576564-Bromo-2,5-dimethyl-1,3-benzothiazole

Reagents, catalysts & solvents 1

HCID 6212ChloroformSolvent

Procedure

A mixture of 2,5-dimethyl-1,3-benzothiazole (10.00 g, 61.26 mmol, Aldrich) and bromine (6.94 mL, 134.8 mmol) in chloroform (200 mL) was heated at reflux overnight. After cooling to room temperature, the mixture was washed with 1 N NaOH, followed by saturated sodium thiosulfate and brine, then dried over sodium sulfate and evaporated to dryness. The residue was purified on silica gel, eluting with 0 to 50% EtOAc in hexane. The first peak had a retention time of 2.51 minutes, LCMS calculated for C9H9BrNS(M+H)+: m/z=242.0; found: 241.9. 1H NMR shown to be the desired product B (980 mg, 6.61%). 1H NMR (CDCl3, 400 MHz) 7.63 (1H, d, J=8.4 Hz), 7.22 (1H, d, J=8.4 Hz), 2.87 (3H, s), 2.55 (3H, s) ppm. The second peak had a retention time of 2.758 minutes, LCMS (M+H)+m/z=241.9; found: 242. 1H NMR showed no coupling for the two phenyl hydrogens confirming the 6-bromo isomer.

Workup

  1. temperaturewas heated
  2. temperatureat reflux overnight
  3. washthe mixture was washed with 1 N NaOH
  4. dry with materialdried over sodium sulfate
  5. customevaporated to dryness
  6. customThe residue was purified on silica gel
  7. washeluting with 0 to 50% EtOAc in hexane

Sources & evidence

ORD record
ord-0ad568de7f144c1bad7775d5328fcff0
Source dataset
uspto-grants-2014_03
Patent number
US08680108B2

Reaction notes

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