Reaktion #87950

Reaktionsgleichung

sodium hydroxide

methyl 7-methoxymethyl-2H-chromene-8-carboxylate

Intermediate 9

methyl 7-methoxymethyl-2H-chromene-8-carboxylate

bromoform

ethyl acetate

→

methyl cis-(1aRS,7bSR)-1,1-dibromo-5-methoxymethyl-1,1a,2,7b-tetrahydrocyclopropa[c]chromene-4-carboxylate

Lösungsmittel

brine

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturAfter cooling
2. 2
   ExtraktionThe aqueous layer was further extracted with ethyl acetate
3. 3
   Trocknenthe combined organic layers were dried (MgSO4)
4. 4
   Filtrationfiltered
5. 5
   SonstigeThe filtrate was evaporated to dryness
6. 6
   Sonstigethe residue was purified by chromatography on silica
7. 7
   Wascheneluting with a mixture of TBME and cyclohexane with a gradient of 0-35%

Vorschrift

Aqueous sodium hydroxide solution (50% w/v, 1.63 mL) was added slowly to a vigorously stirred mixture of methyl 7-methoxymethyl-2H-chromene-8-carboxylate (Intermediate 9, 0.875 g), benzyltriethylammonium chloride (0.173 g) and bromoform (15 mL). The resultant mixture was vigorously stirred and heated at 60° C. for 3 hours. After cooling, the mixture was poured into a mixture of brine and ethyl acetate. The aqueous layer was further extracted with ethyl acetate and the combined organic layers were dried (MgSO4) and filtered. The filtrate was evaporated to dryness and the residue was purified by chromatography on silica, eluting with a mixture of TBME and cyclohexane with a gradient of 0-35% to give methyl cis-(1aRS,7bSR)-1,1-dibromo-5-methoxymethyl-1,1a,2,7b-tetrahydrocyclopropa[c]chromene-4-carboxylate (1.06 g) as a white solid.

Quelle