Reaction #2692

Reaction equation

carbon dioxide

methyl iodide

potassium carbonate

n-Butyllithium

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dithiole

→

4-Methoxycarbonyl-(2,2,6,6-tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dithiole)

Solvents

DMF

ether

Conditions

Workup

1. 1
   workup.ADDITIONfilled
2. 2
   Otherreaction flask
3. 3
   workup.STIRRINGafter stirring overnight
4. 4
   Filtrationthe ether was filtered off
5. 5
   WashThe solid residue was washed with chloroform
6. 6
   Otherdried under vacuum
7. 7
   workup.STIRRINGwas stirred for 1.5 h at 60° C
8. 8
   workup.WAITThe stirring was continued overnight
9. 9
   FiltrationThe mixture was filtered
10. 10
    Otherthe solution evaporated
11. 11
    workup.DISSOLUTIONthe residue was dissolved in dichloromethane
12. 12
    WashThe organic phase was washed with water (2*30 mL)
13. 13
    Dryingdried (Na2SO4)
14. 14
    Otherevaporated
15. 15
    Otherto give
16. 16
    Otherafter additional drying under vacuum a bright green-yellow crystalline pure product

Procedure

2,2,6,6-Tetramethylbenzo[1,2-d:4,5-d']-bis(1,3)dithiole (2.0 g, 6.98 mmol) was dissolved in dry ether (50.0 mL) in a dry, argon filled reaction flask. n-Butyllithium (3.07 mL, 2.5M in hexane) was added and the reaction mixture was stirred for 30 min. The solution was poured onto solid carbon dioxide and, after stirring overnight, the ether was filtered off. The solid residue was washed with chloroform and dried under vacuum. The crude product was mixed with potassium carbonate (0.97 g, 6.98 mmol) in dry DMF (20.0 mL) and was stirred for 1.5 h at 60° C. After cooling to ambient temperature, methyl iodide (0.435 mL, 6.98 mmol) was added. The stirring was continued overnight. The mixture was filtered, the solution evaporated and the residue was dissolved in dichloromethane and water. The organic phase was washed with water (2*30 mL), dried (Na2SO4) and evaporated to give after additional drying under vacuum a bright green-yellow crystalline pure product.

Source