Hydrochloric Acid → 2-Oxocyclopentane-1-carboxylic acid

To methyl 2-oxocyclopentanecarboxylate (5 g, 35.1 mmol) in H2O (7.5 mL), NaOH (1.5 g) was added. The reaction mixture was stirred at room temperature for 40 h, then cooled to 0° C. and conc. HCl (3 mL) was added, then stirred for an additional 30 min. at 0° C. to give 2-oxocyclopentanecarboxylic acid (4.5 g, crude). In another set up, 3,4-dichloroaniline (5.5 g, 33.9 mmol) was dissolved in H2O (22 mL), cooled to 0° C. and conc. HCl (8.3 mL) was added and stirred for 20 min. while maintaining the temperature at 0° C. NaNO2 (2.3 g, 33.9 mmol) in water was added to the reaction mixture and stirred at 0° C. for another 30 min. The reaction mixture was filtered and to the filtrate 2-oxocyclopentanecarboxylic acid (4.5 g, crude) (prepared above) was added slowly. The reaction mixture was slowly warmed to room temperature and stirred for 1 h during which time a solid precipitated out which was filtered to provide the title compound as a yellow solid (5 g, 58%). 1H NMR (200 MHz, CDCl3, δ in ppm) 7.59 (bs, 1H), 7.40-7.30 (m, 2H), 7.09-6.94 (m, 1H), 2.80 (t, J=7.4 Hz, 1H), 2.68 (t, J=7.4 Hz, 1H), 2.55-2.45 (m, 2H), 2.24-2.06 (m, 2H).

1. temperaturecooled to 0° C.
2. stirringstirred for an additional 30 min. at 0° C.

ORD record

ord-ab5b8edd5f0c403a86b1c3f6bfaf6f34

Source dataset

uspto-grants-2015_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08987319B2