Ozone → 2-(2-Oxoethyl)-7-methoxy-4-chromanone

An ozone stream (3 g ozone/hour) was conducted while stirring for 1 hour through a solution, cooled to -70°, of 6.25 g of (RS)-2-(2-buten-1-yl)-7-methoxy-4-chromanone in 90 ml of anhydrous dichloromethane and 30 ml of anhydrous methanol. Subsequently, the solution was flushed with oxygen for 5 minutes and with argon for 15 minutes. After the addition of 3 ml of dimethyl sulfide, the mixture was stirred at room temperature for 16 hours. The reaction mixture was subsequently evaporated in a vacuum. The residue was treated with 60 ml of dichloromethane and, after the addition of 15 ml of water and 15 ml of trifluoroacetic acid, stirred at room temperature for 3 hours. The mixture was subsequently poured into 100 ml of water and neutralized while stirring by the spatula-wise addition of sodium hydrogen carbonate. An additional 70 ml of water were added. The phases were separated and the aqueous phase was extracted twice with 100 ml of dichloromethane each time. The combined organic phases were dried over magnesium sulfate and concentrated in a vacuum. 2.9 g (49%) of 2-(2-oxoethyl)-7-methoxy-4-chromanone were obtained as a yellow oil.

1. customSubsequently, the solution was flushed with oxygen for 5 minutes and with argon for 15 minutes
2. additionAfter the addition of 3 ml of dimethyl sulfide
3. stirringthe mixture was stirred at room temperature for 16 hours
4. customThe reaction mixture was subsequently evaporated in a vacuum
5. additionThe residue was treated with 60 ml of dichloromethane
6. additionafter the addition of 15 ml of water and 15 ml of trifluoroacetic acid
7. stirringstirred at room temperature for 3 hours
8. additionThe mixture was subsequently poured into 100 ml of water
9. stirringneutralized while stirring by the spatula-wise addition of sodium hydrogen carbonate
10. additionAn additional 70 ml of water were added
11. customThe phases were separated
12. extractionthe aqueous phase was extracted twice with 100 ml of dichloromethane each time
13. dry with materialThe combined organic phases were dried over magnesium sulfate
14. concentrationconcentrated in a vacuum

ORD record

ord-e7ee94e7355947e9943c279b7a996a2a

Source dataset

uspto-grants-1997_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05646173