Boron tribromide → 2-(4-bromo-5-chloro-2-hydroxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

HRID 2260927Notes

Reaction equation

HRID 2260927 reaction equation
B(Br)(Br)Br.[Br:5][C:6]1[C:11]([Cl:12])=[CH:10][C:9]([N:13]2[C:17](=[O:18])[NH:16][C:15]([C:19]3[S:20][C:21]([Br:24])=[CH:22][CH:23]=3)=[N:14]2)=[C:8]([O:25]C)[CH:7]=1>ClCCl>[Br:5][C:6]1[C:11]([Cl:12])=[CH:10][C:9]([N:13]2[C:17](=[O:18])[NH:16][C:15]([C:19]3[S:20][C:21]([Br:24])=[CH:22][CH:23]=3)=[N:14]2)=[C:8]([OH:25])[CH:7]=1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 1358250532-(4-bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one4×

Product 1

HCID 1355466422-(4-bromo-5-chloro-2-hydroxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-oneYield 81%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
-78 °C

Procedure

2-(4-Bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one (Intermediate 3) (1.395 g) was suspended in anhydrous dichloromethane (20-25 mL/mmol of Intermediate 3) under argon and cooled to −78° C. A 1 M solution of BBr3 (9 mL) in anhydrous dichloromethane was added via a dropping funnel over a 45 minute period. After the addition was complete, the reaction was warmed to room temperature and stirred for 5 hours. The reaction was quenched by the addition of 5-10 mL water. Volatile solvent was removed under vacuum and the crude product was filtered and washed with water. The solid was refluxed in a mixture of acetone and ethanol for 15 minutes. After cooling to room temperature, the purified product was filtered and washed with acetone and ethanol. The solid was dried under high vacuum to yield 1.1 g (81%) of the desired product, Compound II.

Workup

  1. additionAfter the addition
  2. temperaturethe reaction was warmed to room temperature
  3. customThe reaction was quenched by the addition of 5-10 mL water
  4. customVolatile solvent was removed under vacuum
  5. filtrationthe crude product was filtered
  6. washwashed with water
  7. temperatureThe solid was refluxed in a mixture of acetone and ethanol for 15 minutes
  8. temperatureAfter cooling to room temperature
  9. filtrationthe purified product was filtered
  10. washwashed with acetone and ethanol
  11. customThe solid was dried under high vacuum

Sources & evidence

ORD record
ord-79bd88f85ffc4fa5a749b66de40932b9
Source dataset
uspto-grants-2010_12
Patent number
US07846671B2

Reaction notes

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