Reaction #1836

Reaction equation

Cyclohexene

bromine

2-[2-(1H-tetrazol-5-yl)phenyl]-5-methylbenzofuran

1,4-dioxane

→

product

Yield 85.0%

3-Bromo-2-[2-(1H-tetrazol-5-yl)phenyl]-5-methylbenzofuran

Yield 85.0%

Solvents

carbon tetrachloride

Conditions

Workup

1. 1
   OtherA 1 L 3-neck round bottom flask equipped with a magnetic stirrer
2. 2
   Concentrationit was concentrated under vacuum to an oily residue that
3. 3
   Otherwas partitioned between 100 mL of 1N aqueous sodium hydroxide and 100 mL of ether
4. 4
   OtherThe aqueous layer was removed
5. 5
   Extractionextracted several times with ethyl acetate
6. 6
   WashThe combined extracts were washed with saturated aqueous sodium chloride
7. 7
   Dryingdried over magnesium sulfate
8. 8
   Filtrationfiltered
9. 9
   Concentrationconcentrated under vacuum
10. 10
    Otherto give a white foam that
11. 11
    Otherwas triturated with 100 mL of hot toluene
12. 12
    TemperatureThe mixture was cooled in an ice bath
13. 13
    Otherthe solids removed by filtration
14. 14
    Washthen washed with cold toluene, air
15. 15
    Otherdried
16. 16
    Otherdried under vacuum

Procedure

A 1 L 3-neck round bottom flask equipped with a magnetic stirrer, thermometer, dropping funnel and nitrogen bubbler was charged with 12.97 g (46.9 mmol) of 2-[2-(1H-tetrazol-5-yl)phenyl]-5-methylbenzofuran and 500 mL of 1,4-dioxane. To the well-stirred solution at room temperature was added a solution of 4.8 mL (93.2 mmol) of bromine in 35 mL of carbon tetrachloride dropwise over 1 hour. Cyclohexene (16 mL) was added to the reaction mixture then it was concentrated under vacuum to an oily residue that was partitioned between 100 mL of 1N aqueous sodium hydroxide and 100 mL of ether. The aqueous layer was removed, acidified with 50 mL of 2N aqueous hydrochloric acid, and extracted several times with ethyl acetate. The combined extracts were washed with saturated aqueous sodium chloride, dried over magnesium sulfate, filtered and concentrated under vacuum to give a white foam that was triturated with 100 mL of hot toluene. The mixture was cooled in an ice bath and the solids removed by filtration then washed with cold toluene, air dried and dried under vacuum to give 14.11 g (39.7 mmol, 85%) of product. 1H NMR (200 MHz,CDCl3 +1 drop DMSO-d6): 2.44 (s,3H), 7.1-7.3 (m,4H), 7.6 (m,2H), 7.86 (m,1H), 7.95 (m,1H).

Source