Reacción #320802

Ecuación de reacción

NaOEt

1,4-dimethoxy-2,3-dibromomethylbenzene

ethyl 2-mercaptoacetate

sodium methoxide

→

title compound

Rendimiento 45.0%

3-carbomethoxy-5,8-dimethoxyisothiochroman

Rendimiento 45.0%

Disolventes

CH2Cl2

MeOH

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroAfter 5 minutes the solvent was evaporated
2. 2
   workup.DISSOLUTIONthe crude was redissolved in THF (400 ml)
3. 3
   Temperaturacooled to 0° C. again
4. 4
   OtroThe ice bath was removed
5. 5
   workup.STIRRINGthe reaction was stirred for 2 more hours
6. 6
   OtroThe reaction mixture was then quenched with NH4Cl (sat.)
7. 7
   Extracciónextracted with ether
8. 8
   Secadodried over MgSO4
9. 9
   Filtraciónfiltered
10. 10
    Concentraciónconcentrated
11. 11
    workup.ADDITIONThe crude residue was then treated with NaOME in MeOH
12. 12
    ExtracciónThe reaction mixture was extracted with ether (100 ml×2)
13. 13
    LavadoThe combined organic phases were washed with H2O
14. 14
    Secadodried over MgSO4
15. 15
    Filtraciónfiltered
16. 16
    Concentraciónconcentrated to a residue that
17. 17
    Otrowas purified by flash chromatography

Procedimiento

1,4-dimethoxy-2,3-dibromomethylbenzene (10.0 g, 30.88 mmol) was dissolved in CH2Cl2 and MeOH (750 ml, 6:4) followed by addition of ethyl 2-mercaptoacetate (4.02 ml, 37.06 mmol) with stirring under argon. The mixture was then cooled to 0° C. followed by dropwise addition of sodium methoxide (4.37M, 8.5 ml, 37.06 mmol) over a period of 2 h using an automatic syringe pump. After 5 minutes the solvent was evaporated and the crude was redissolved in THF (400 ml) and cooled to 0° C. again. NaOEt (2.10 g, 30.88 mmol) was then added. The ice bath was removed and the reaction was stirred for 2 more hours. The reaction mixture was then quenched with NH4Cl (sat.) and extracted with ether. The organic phases were combined, dried over MgSO4, filtered and concentrated. The crude residue was then treated with NaOME in MeOH and THF at 0° C. for 2 hours. The reaction mixture was extracted with ether (100 ml×2). The combined organic phases were washed with H2O, dried over MgSO4, filtered and concentrated to a residue that was purified by flash chromatography to give title compound in 45% yield. 1H NMR (300 MHz, CDCl3, ppm) d:2.97 (dd, 1H, J=16.51, 8.79 Hz, HCHaCHC=O), 3.36 (dd, 1H, J=16.7, 5.1 Hz, HCHeCHC=O), 3.73 (m, 2H, HCHa,e--O), 3.75 (s, 3H, OCH3), 3.78 (s, 6H, 2×OCH3), 3.85 (m, 1H, HC--S), 6.69 (m, 2H, ArH).

Fuente