Camphor → HCID 67126910, compound

Temperature

100 °C

A mixture of D-(+)-camphor (4.40 g, 28.9 mmol) and sodium amide (2.50 g, 61.5 mmol) in toluene (100 mL) was stirred at 100° C. for 30 min. A solution of 1,3-dibromopropane (31.8 mmol, 3.24 mL, 6.42 g) in toluene (20 mL) was added, and the reaction was heated at reflux for 3 h. The reaction was cooled to ambient temperature, washed with water (100 mL), dried over anhydrous sodium sulfate and concentrated. The residue was dissolved in 5% methanol in dichloromethane (80 mL) and cooled to −78°C. Ozone was passed through the solution until the blue color persisted (˜10 minutes). Dimethyl sulfide (2 mL) was then added, and the reaction was warmed slowly to ambient temperature. The reaction mixture was concentrated, and the residue was purified on a silica gel column (40 g), eluting with 0-20% ether in hexanes, to obtain (1S,4R)-4,7,7-trimethylspiro[bicyclo[2.2.1]heptane-2,1′-cyclobutan]-3-one (1.66 g, 29.9% yield) as oil. 1H NMR (CDCl3, 400 MHz): δ 2.26 (m, 1H), 2.10-1.97 (m, 5H), 1.85-1.1.66 (m, 2H), 1.62-1.53 (m, 1H), 1.47-1.40 (m, 1H), 1.28-1.19 (m, 1H), 0.94 (s, 3H), 0.88 (s, 3H), 0.75 (s, 3H); LCMS (m/z): 193 (M+1).

1. temperaturethe reaction was heated
2. temperatureat reflux for 3 h
3. temperatureThe reaction was cooled to ambient temperature
4. washwashed with water (100 mL)
5. dry with materialdried over anhydrous sodium sulfate
6. concentrationconcentrated
7. dissolutionThe residue was dissolved in 5% methanol in dichloromethane (80 mL)
8. temperaturecooled to −78°C
9. custom(˜10 minutes)
10. additionDimethyl sulfide (2 mL) was then added
11. temperaturethe reaction was warmed slowly to ambient temperature
12. concentrationThe reaction mixture was concentrated
13. customthe residue was purified on a silica gel column (40 g)
14. washeluting with 0-20% ether in hexanes

ORD record

ord-95644938569f4baabf6b18861f93bb3b

Source dataset

uspto-grants-2014_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08809397B2