Reaction #2708

Reaction equation

pTSA

3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone

Compound A

3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone

6-methyl-3-bromopyridine

n-BuLi

hexane

→

title compound

1-(6-Methyl-pyrid-3-yl)-3,4-dihydro-4,4-dimethyl-7-bromo-naphthalene

Solvents

THF

ethyl acetate

ethyl acetate

THF

Conditions

Workup

1. 1
   workup.ADDITIONThis mixture was added to a flask
2. 2
   Otherat -78° C
3. 3
   workup.STIRRINGstirred for 16 hours
4. 4
   Washwashed with water (10 mL), brine (10 mL)
5. 5
   Dryingdried with MgSO4
6. 6
   OtherSolvent was removed by distillation
7. 7
   workup.DISSOLUTIONthe crude material was dissolved in toluene (25 mL)
8. 8
   TemperatureThe mixture was heated at 90° C. for 36 hours
9. 9
   Washwashed with 10% NaHCO3 (2×10 mL), brine (10 mL)
10. 10
    Dryingdried with MgSO4
11. 11
    Otherthe solvent was removed by evaporation

Procedure

To a cold (-78° C.) solution of 6-methyl-3-bromopyridine (890 mg, 5.2 mmol) in THF (15 mL) was added n-BuLi in hexane (1.6M solution, 3.5 mL, 5.6 mmol) and stirred for 1 hour. This mixture was added to a flask containing 3,4-dihydro-4,4-dimethyl-7-bromo-1(2H)-naphthalenone (Compound A, 1.35 g, 5.4 mmol), in THF (5 mL) at -78° C. The reaction mixture was gradually warmed to ambient temperature and stirred for 16 hours. Thereafter it was diluted with ethyl acetate (100 mL), washed with water (10 mL), brine (10 mL) and dried with MgSO4. Solvent was removed by distillation, the crude material was dissolved in toluene (25 mL) and pTSA (530 mg, 2.8 mmol) was added. The mixture was heated at 90° C. for 36 hours. Thereafter it was diluted with ethyl acetate (100 mL), washed with 10% NaHCO3 (2×10 mL), brine (10 mL), dried with MgSO4 and the solvent was removed by evaporation. The title compound was obtained by recrystallization from ethyl acetate and hexane mixture (1:9).

Source