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 150 mL of acetic acid and cooled by ice water. Then 45 g of zinc powder were 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 150 mL of acetic acid
5. temperaturecooled by ice water
6. additionThen 45 g of zinc powder were 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-e819532a1cea4b9aaf4a7c1f287bcb8a

Source dataset

uspto-grants-2011_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08003651B2