Reacción #347900

Ecuación de reacción

n-butyl lithium

n-hexane

dry ice

dry ice

6-bromo-5-methyl-1,4-benzodioxane

→

5-methyl-1,4-benzodioxan-6-carboxylic acid

Rendimiento 77.0%

Disolventes

Water

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONthe reaction mixture was poured
2. 2
   workup.STIRRINGwhile stirring
3. 3
   Otrothe tetrahydrofuran was removed under reduced pressure
4. 4
   LavadoThe resulting alkaline aqueous solution was washed with methylene chloride
5. 5
   Filtraciónthe precipitated crystals were collected by filtration
6. 6
   Otrodried

Procedimiento

In 300 ml of dry tetrahydrofuran, was dissolved 32.0 g of 6-bromo-5-methyl-1,4-benzodioxane and after cooling the solution to -78° C., 96.7 ml of n-butyl lithium (n-hexane solution)was added dropwise over 20 minutes or more. After stirring at the same temperature for 1.5 hours, the reaction mixture was poured onto crushed dry ice and dry ice was sublimated while stirring. Water was added to the -mixture and the tetrahydrofuran was removed under reduced pressure. The resulting alkaline aqueous solution was washed with methylene chloride and adjusted to pH 3 with a 5% hydrochloric acid, and the precipitated crystals were collected by filtration and dried to obtain 20.9 g of 5-methyl-1,4-benzodioxan-6-carboxylic acid (yield: 77%).

Fuente