Hydrochloric Acid → Ethyl 5-methyl-2-oxo-2,3-dihydro-1H-imidazole-4-carboxylate

A mixture of ethyl (2E)-2-(hydroxyimino)-3-oxobutanoate (8.50 g, 53.41 mmol) and 10% Pd/C (0.42 g) in EtOH (25 mL) and a 1.5 M solution of HCl (40 mL) were stirred under hydrogen (50 psig) for 4 h. The vessel was carefully vented then the mixture was filtered through Celite which was subsequently washed with EtOH. The filtrate was concentrated slightly to remove some of the EtOH but the water bath was kept below 40° C. A 5M solution of aqueous HCl (5 mL) was added to the yellow solution and this was added dropwise to a solution of KOCN (6.50 g, 80.12 mmol) in water (25 mL) at RT. The reaction mixture was stirred at RT for 3 days then cooled to 0° C. After 2 h, the precipitate was filtered and washed with a cold 1:1 mixture of MeOH/water (20 mL) and dried under vacuum to afford 1.70 g (19%) of the title compound as a grey powder. 1H NMR (400 MHz, DMSO-d6) δ ppm 10.61 (br. s., 1H), 10.14 (br. s., 1H), 4.16 (d, 2H), 2.20 (br. s., 3H), 1.23 (t, 3H). LCMS m/z 171.3 (M+H).

1. filtrationthe mixture was filtered through Celite which
2. washwas subsequently washed with EtOH
3. concentrationThe filtrate was concentrated slightly
4. customto remove some of the EtOH
5. customwas kept below 40° C
6. additionA 5M solution of aqueous HCl (5 mL) was added to the yellow solution
7. temperaturethen cooled to 0° C
8. waitAfter 2 h
9. filtrationthe precipitate was filtered
10. washwashed with a cold 1:1 mixture of MeOH/water (20 mL)
11. customdried under vacuum

ORD record

ord-b3d87bc13d754d8d828185c99646aaba

Source dataset

uspto-grants-2012_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08304419B2