CAS No 75706-12-6 , 5-methyl-N-[4-(trifluoromethyl)phenyl]-1,2-oxazole-4-carboxamide

Title: Leflunomide
CAS Registry Number: 75706-12-6
CAS Name: 5-Methyl-N-[4-(trifluoromethyl)phenyl]-4-isoxazolecarboxamide
Synonyms: a,a,a-trifluoro-5-methyl-4-isoxazolecarboxy-p-toluidide; 5-methylisoxazole-4-carboxylic acid trifluoromethylanilide
Manufacturers' Codes: HWA-486
Trademarks: Arava (Sanofi-Aventis)
Molecular Formula: C12H9F3N2O2
Molecular Weight: 270.21
Percent Composition: C 53.34%, H 3.36%, F 21.09%, N 10.37%, O 11.84%
Literature References: Disease modifying antirheumatic drug (DMARD) with immunosuppressant activity. Converted in vivo to its active open ring metabolite, teriflunomide, q.v. Inhibits de novo pyrimidine biosynthesis in immune cells. Prepn: F. J. Kaemmerer, R. Schleyerbach, DE 2854439; eidem, US 4284786 (1980, 1981 both to Hoechst); and pharmacology: P. Fossa et al., Farmaco 46, 789 (1991). HPLC determn of active metabolite in plasma: V. C. Dias et al., Ther. Drug Monit. 17, 84 (1995). Review of mechanisms of action: R. I. Fox, J. Rheumatol. 25, Suppl. 53, 20-26 (1998); of clinical pharmacology: B. Rozman, ibid. 27-32. Clinical trial in rheumatoid arthritis: V. Strand et al., Arch. Intern. Med. 159, 2542 (1999). Reviews: C. Miceli-Richard, M. Dougados, Expert Opin. Pharmacother. 4, 987-997 (2003); J. P. Kaltwasser, F. Behrens, ibid. 6, 787-801 (2005).
Properties: Crystals from toluene, mp 166.5°. pKa 10.8. Soly in water (25°): 25 - 27 mg/l. Sol in methanol, ethanol, acetone.
Melting point: mp 166.5°
pKa: pKa 10.8
Therap-Cat: Antirheumatic.
Keywords: Antiarthritic/Antirheumatic; Immunomodulator.