Reaction #42731

Reaction equation

product

6-Bromo-2,2-dimethyl-4H-benzo[1,3]dioxine

n-butyllithium

N-methyl-N-methoxy acetamide

→

title compound

6-Acetyl-2,2-dimethyl-4H-benzo[1,3]dioxine

Solvents

ethyl acetate

—

hexanes

—

hexanes

THF

Conditions

Workup

1. 1
   workup.WAITAfter 2 hours
2. 2
   Otherthe reaction mixture was quenched with water
3. 3
   workup.ADDITIONdiluted with 2.0 L of 1.0 M aqueous phosphate buffer (pH=7.0)
4. 4
   Extractionextracted once with diethyl ether
5. 5
   WashThe diethyl ether phase was washed once with brine
6. 6
   Dryingdried over Na2SO4
7. 7
   Filtrationfiltered
8. 8
   Concentrationconcentrated under reduced pressure
9. 9
   Otherto give a light orange oil

Procedure

To the product of step (a) (110 g, 0.46 mol) in 1.0 L of THF at −78° C. was added 236 mL (0.51 mol) of 2.14 M n-butyllithium in hexanes via a dropping funnel. After 30 minutes, N-methyl-N-methoxy acetamide (71 g, 0.69 mol, available from TCI) was added. After 2 hours, the reaction mixture was quenched with water, diluted with 2.0 L of 1.0 M aqueous phosphate buffer (pH=7.0) and extracted once with diethyl ether. The diethyl ether phase was washed once with brine, dried over Na2SO4, filtered and concentrated under reduced pressure to give a light orange oil. The oil was dissolved in a minimum volume of ethyl acetate, diluted with hexanes, and to give the title compound as a crystalline solid.

Source