Reaktion #592822

Reaktionsgleichung

sodium thiosulfate

6-methoxy-2,2-dimethyl-7-nitro-2H-1-benzopyran

N-methyl imidazole

iodosobenzene

→

aimed product

Ausbeute 75.0%

(3R*,4R*)-3,4-Epoxy-6-methoxy-2,2-dimethyl-7-nitro-3,4-dihydro-2H-1-benzopyran

Ausbeute 75.0%

Lösungsmittel

acetonitrile

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwere added at room temperature
2. 2
   SonstigeUpon the completion of the reaction
3. 3
   Filtrationthe resulting solution was filtered through celite
4. 4
   ExtraktionThe resulting filtrate extracted with ethyl acetate
5. 5
   WaschenThe organic phase was washed with water and sodium chloride solution
6. 6
   Trocknendried over anhydrous magnesium sulfate
7. 7
   workup.DISTILLATIONAfter distilling off the solvent
8. 8
   Sonstigethe residue was purified by column chromatography (hexane/ethyl acetate=4/1)

Vorschrift

To a solution (300 mL) of acetonitrile containing 6-methoxy-2,2-dimethyl-7-nitro-2H-1-benzopyran (10.0 g, 42.5 mmol), N-methyl imidazole (0.678 mL, 8.50 mmol), (R,R,S,S)-Ph,Ph salen manganese complex (XY) (880 mg, 0.850 mmol) and iodosobenzene (18.7 mg, 85.0 mmol) were added at room temperature and the mixture was stirred for 2 hours. Upon the completion of the reaction, an aqueous solution of sodium thiosulfate was added to the reaction solution, the resulting solution was filtered through celite. The resulting filtrate extracted with ethyl acetate. The organic phase was washed with water and sodium chloride solution, and then dried over anhydrous magnesium sulfate. After distilling off the solvent, the residue was purified by column chromatography (hexane/ethyl acetate=4/1) and the aimed product was obtained as yellow crystals (yield: 75%, optical purity: 99.7% ee).

Quelle