Ethyl (2R)-2-methyl-5-(propan-2-ylidene)cyclopentane-1-carboxylate → Ethyl (2R)-2-methyl-5-oxocyclopentane-1-carboxylate

(2R)-Ethyl 2-methyl-5-(propan-2-ylidene)cyclopentanecarboxylate (24 g, 0.122 mol) in ethyl acetate (100 mL) was cooled to −68° C. with dry ice/isopropanol. Ozonized oxygen (5-7 ft3h−1 of O2) was bubbled through the solution for 3.5 hours. The reaction mixture was flushed with nitrogen at room temperature until the color disappeared. The ethyl acetate was removed under vacuum, and the residue was dissolved in acetic acid (150 mL) and cooled by ice water. Zinc powder (45 g) was then added. The solution was stirred for 30 minutes and then filtered. The filtrate was neutralized with 2N NaOH (1.3 L) and NaHCO3. The aqueous phase was extracted with ether (3×200 mL). The organic phase was combined, washed with water, dried and concentrated to afford (2R)-ethyl 2-methyl-5-oxocyclopentanecarboxylate (20 g, 96%). 1H NMR (CDCl3, 400 MHz) δ 4.21 (m, 2H), 2.77 (d, J=11.2 Hz, 1H), 2.60 (m, 1H), 2.50-2.10 (m, 3H), 1.42 (m, 1H), 1.33 (m, 3H), 1.23 (m, 3H).

1. customOzonized oxygen (5-7 ft3h−1 of O2) was bubbled through the solution for 3.5 hours
2. customThe reaction mixture was flushed with nitrogen at room temperature until the color
3. customThe ethyl acetate was removed under vacuum
4. dissolutionthe residue was dissolved in acetic acid (150 mL)
5. temperaturecooled by ice water
6. additionZinc powder (45 g) was then added
7. filtrationfiltered
8. extractionThe aqueous phase was extracted with ether (3×200 mL)
9. washwashed with water
10. customdried
11. concentrationconcentrated

ORD record

ord-1ca75867a8db46c292230a55758a3d9b

Source dataset

uspto-grants-2013_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08377937B2