Reaction #2348109

Reaction equation

Intermediate 3

2-(4-bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

2-(4-Bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

2-(4-bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

BBr3

Intermediate 3

2-(4-bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

dichloromethane

2-(4-bromo-5-chloro-2-methoxyphenyl)-2,4-dihydro-5-(5-bromothien-2-yl)-3H-1,2,4-triazol-3-one

→

desired product

Yield 81.0%

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

Yield 81.0%

Solvents

dichloromethane

Conditions

Workup

1. 1
   workup.ADDITIONAfter the addition
2. 2
   Temperaturethe reaction was warmed to room temperature
3. 3
   OtherThe reaction was quenched by the addition of 5-10 mL water
4. 4
   OtherVolatile solvent was removed under vacuum
5. 5
   Filtrationthe crude product was filtered
6. 6
   Washwashed with water
7. 7
   TemperatureThe solid was refluxed in a mixture of acetone and ethanol for 15 minutes
8. 8
   TemperatureAfter cooling to room temperature
9. 9
   Filtrationthe purified product was filtered
10. 10
    Washwashed with acetone and ethanol
11. 11
    OtherThe solid was dried under high vacuum

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.

Source