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 ft3 h− 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 150 mL of acetic acid and cooled by ice water, and zinc powder (45 g) was 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 ft3 h− 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 150 mL of acetic acid
5. temperaturecooled by ice water, and zinc powder (45 g)
6. additionwas 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-c5f46323ac064f2bbd44d40346b23b6d

Source dataset

uspto-grants-2011_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08063050B2