Trifluoroacetic anhydride → (1R,5S)-6,6-Dimethyl-3-oxabicyclo(3.1.0)hexane-2,4-dione

To a solution containing the product (caronic acid) of step 1 (10 g) in toluene (35 mL) was added trifluoroacetic anhydride (17.9 mL) over 10 min. The mixture was heated to reflux while simultaneously distilling out trifluoroacetic acid and excess trifluoroacetic anhydride. When the temperature reached 100-110° C., additional toluene (20 mL) was added and the reaction mixture was heated under reflux. After 3 h, the mixture was concentrated to about 30 mL. Toluene (70 mL) was added and the mixture once again concentrated to about 30 mL. This solution which contained the compound of formula II (assayed by 1H NMR using ρ-nitromethylbenzoate as an internal std) was used in the first step of Example 2 without further purification. Alternatively, the compound formula II can be purified by methods such as fractional distillation.

1. temperatureThe mixture was heated
2. temperatureto reflux
3. distillationwhile simultaneously distilling out trifluoroacetic acid and excess trifluoroacetic anhydride
4. customreached 100-110° C.
5. additionadditional toluene (20 mL) was added
6. temperaturethe reaction mixture was heated
7. temperatureunder reflux
8. concentrationthe mixture was concentrated to about 30 mL
9. additionToluene (70 mL) was added
10. concentrationthe mixture once again concentrated to about 30 mL
11. customwas used in the first step of Example 2 without further purification
12. distillationAlternatively, the compound formula II can be purified by methods such as fractional distillation

ORDレコード

ord-027d828791874cee9539fb9290d4f67e

出典データセット

uspto-grants-2009_08

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US07569705B2