Reaction #2710

Reaction equation

2,2-dimethyl-6-bromo-thiochroman-4-one

Compound M

2,2-dimethyl-6-bromo-thiochroman-4-one

pTSA

4-bromotoluene

t-BuLi

pentane

→

title compound

2,2-Dimethyl-4(tol-4-yl)-6-bromo-thiochrom-3-ene

Solvents

THF

ethylacetate

dichloromethane

THF

Conditions

Workup

1. 1
   workup.ADDITIONThis mixture was added to a flask
2. 2
   workup.STIRRINGand stirred for 16 hours at ambient temperature
3. 3
   OtherThe reaction was quenched
4. 4
   workup.ADDITIONby adding aq. NH4Cl
5. 5
   Extractionthe resulting mixture was extracted with ethylacetate
6. 6
   Washwashed with brine
7. 7
   Otherdried
8. 8
   Otherthe solvent was removed by evaporation
9. 9
   OtherThe product was isolated by chromatography on silica gel
10. 10
    Temperatureheated to 50° C. for 3 hours
11. 11
    Washwashed with 10% NaHCO3 (5 mL), brine (5 mL)
12. 12
    Dryingdried with MgSO4
13. 13
    Otherthe solvent was removed by evaporation

Procedure

To a cold (-78° C.) solution of 4-bromotoluene (720 mg, 4.2 mmol) in THF (8 mL) was added t-BuLi in pentane (1.7M, 0.5 mL, 0.85 mmol). The mixture was warmed to ambient temperature over 30 minutes with stirring. This mixture was added to a flask containing 2,2-dimethyl-6-bromo-thiochroman-4-one (Compound M, 140 mg, 0.4 mmol) and THF (2 mL). and stirred for 16 hours at ambient temperature. The reaction was quenched by adding aq. NH4Cl, and the resulting mixture was extracted with ethylacetate, washed with brine, dried and the solvent was removed by evaporation. The product was isolated by chromatography on silica gel. The material was dissolved in dichloromethane (5 mL) and pTSA (5 mg) was added and heated to 50° C. for 3 hours. The misture was diluted with ethylacetate (20 mL), washed with 10% NaHCO3 (5 mL), brine (5 mL), dried with MgSO4 and the solvent was removed by evaporation to afford the title compound as an off.

Source