Product Name

  • Name

    Leflunomide

  • EINECS 616-254-6
  • CAS No. 75706-12-6
  • Article Data21
  • CAS DataBase
  • Density 1.392 g/cm3
  • Solubility
  • Melting Point 163-168 °C
  • Formula C12H9F3N2O2
  • Boiling Point 289.3 °C at 760 mmHg
  • Molecular Weight 270.211
  • Flash Point 128.8 °C
  • Transport Information UN 2811 6.1/PG 3
  • Appearance off white crystalline solid
  • Safety 26-36
  • Risk Codes 22-36/37/38
  • Molecular Structure Molecular Structure of 75706-12-6 (Leflunomide)
  • Hazard Symbols HarmfulXn, IrritantXi
  • Synonyms 4-Isoxazolecarboxamide, 5-methyl-N-(4-(trifluoromethyl)phenyl)-;N-(4-Trifluoromethylphenyl)-5-methylisoxazole-4-carboxamide;Leflunomidum [INN-Latin];sell leflunomide;5-methyl-N-[4-(trifluoromethyl)phenyl]oxazole-4-carboxamide;5-Methylisoxazole-4-(4-trifluoromethyl) carboxanilide;Leflunamide;Isoxazole-4-carboxamide, 5-methyl-N-[4-(trifluoromethyl)phenyl]-;5-Methylisoxazole-4-carboxylic acid (4-trifluoromethyl)anilide;Arava;Leflunomida [INN-Spanish];
  • PSA 55.13000
  • LogP 3.32710

Synthetic route

C40H45AuF6N4O2

C40H45AuF6N4O2

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With tris(pentafluorophenyl)borate In dichloromethane at 40℃;98%
5-methyl-1,2-oxazole-4-carboxylic acid
42831-50-5

5-methyl-1,2-oxazole-4-carboxylic acid

4-trifluoromethylphenylamine
455-14-1

4-trifluoromethylphenylamine

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With triethylamine; 1,1'-carbonyldiimidazole In dichloromethane at 0℃; Reagent/catalyst; Heating;94%
5-methylisoxazole-4-carbonyl chloride
67305-24-2

5-methylisoxazole-4-carbonyl chloride

4-trifluoromethylphenylamine
455-14-1

4-trifluoromethylphenylamine

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
In diethyl ether for 0.5h; Ambient temperature;93%
With sodium hydrogencarbonate In N,N-dimethyl acetamide; toluene86%
With sodium hydrogencarbonate In water; toluene at 20 - 60℃; for 18h;43%
4-trifluoromethylphenylamine
455-14-1

4-trifluoromethylphenylamine

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Stage #1: 5-methyl-1,2-oxazole-4-carboxylic acid With thionyl chloride; N,N-dimethyl-formamide In toluene at 25 - 70℃; for 6h;
Stage #2: 4-trifluoromethylphenylamine In toluene at 0 - 30℃; for 6h;
62.34%
N-(4-aminophenyl)-5-methylisoxazole-4-carboxamide
210627-03-5

N-(4-aminophenyl)-5-methylisoxazole-4-carboxamide

Umemoto's reagent

Umemoto's reagent

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With copper; isopentyl nitrite In acetonitrile at 0 - 15℃; for 8h; Sandmeyer Reaction; Schlenk technique; Inert atmosphere;58%
With copper; isopentyl nitrite In acetonitrile at 0 - 15℃; Sandmeyer Reaction; Inert atmosphere;58%
5-methyl-1,2-oxazole-4-carboxylic acid
42831-50-5

5-methyl-1,2-oxazole-4-carboxylic acid

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: 96 percent / SOCl2 / 1 h / 70 °C
2: 93 percent / diethyl ether / 0.5 h / Ambient temperature
View Scheme
Multi-step reaction with 3 steps
1: thionyl chloride / dichloromethane / 4 h / 40 °C
2: triethylamine / dichloromethane / 0 °C
3: copper; isopentyl nitrite / acetonitrile / 8 h / 0 - 15 °C / Schlenk technique; Inert atmosphere
View Scheme
Multi-step reaction with 2 steps
1: thionyl chloride / 4 h / 50 °C / Inert atmosphere
2: sodium hydrogencarbonate / water; toluene / 18 h / 20 - 60 °C
View Scheme
Multi-step reaction with 2 steps
1: thionyl chloride / 45 °C
2: caesium carbonate / butanone; water / 1 h / 45 - 55 °C
View Scheme
4-trifluoromethylphenylamine
455-14-1

4-trifluoromethylphenylamine

A

5-methylisoxazole-4-carbonyl chloride
67305-24-2

5-methylisoxazole-4-carbonyl chloride

B

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With sodium hydrogencarbonate In water
4-methylisoxazole-4-carbonyl chloride

4-methylisoxazole-4-carbonyl chloride

4-trifluoromethylphenylamine
455-14-1

4-trifluoromethylphenylamine

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
In acetonitrile
5-methyl-1,2-oxazole-4-carboxylic acid
42831-50-5

5-methyl-1,2-oxazole-4-carboxylic acid

4-aminobenzotrifluoride hydrochloride
90774-69-9

4-aminobenzotrifluoride hydrochloride

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Stage #1: 5-methyl-1,2-oxazole-4-carboxylic acid With 1,1'-carbonyldiimidazole In neat (no solvent) for 0.333333h; Milling;
Stage #2: 4-aminobenzotrifluoride hydrochloride In neat (no solvent) for 5h; Milling;
Stage #1: 5-methyl-1,2-oxazole-4-carboxylic acid With 1,1'-carbonyldiimidazole for 0.333333h; Milling; Green chemistry;
Stage #2: 4-aminobenzotrifluoride hydrochloride for 5h; Milling; Green chemistry;
C5H4ClNO3

C5H4ClNO3

1,4-phenylenediamine
106-50-3

1,4-phenylenediamine

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: triethylamine / dichloromethane
2: copper; isopentyl nitrite / acetonitrile / 8 h / 0 - 15 °C / Schlenk technique; Inert atmosphere
View Scheme
5-methylisoxazole-4-carbonyl chloride
67305-24-2

5-methylisoxazole-4-carbonyl chloride

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: triethylamine / dichloromethane / 0 °C
2: copper; isopentyl nitrite / acetonitrile / 8 h / 0 - 15 °C / Schlenk technique; Inert atmosphere
View Scheme
2-ethoxymethyleneacetoacetyl-(4-trifluoromethyl)aniline
75706-11-5

2-ethoxymethyleneacetoacetyl-(4-trifluoromethyl)aniline

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With hydroxylamine hydrochloride; sodium hydroxide In ethanol for 1h; Reflux;
3-oxo-N-(4-(trifluoromethyl)phenyl)butanamide
351-87-1

3-oxo-N-(4-(trifluoromethyl)phenyl)butanamide

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: acetic anhydride / 2 h / 105 °C
2: hydroxylamine hydrochloride; sodium hydroxide / ethanol / 1 h / Reflux
View Scheme
diphenylzinc
1078-58-6

diphenylzinc

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 4 steps
1: toluene / 40 °C
2: tetramethylammonium nitrate; trifluoroacetic anhydride / dichloromethane / 0 °C
3: triethylamine / dichloromethane
4: tris(pentafluorophenyl)borate / dichloromethane / 40 °C
View Scheme
C35H41AuF6N2

C35H41AuF6N2

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 3 steps
1: tetramethylammonium nitrate; trifluoroacetic anhydride / dichloromethane / 0 °C
2: triethylamine / dichloromethane
3: tris(pentafluorophenyl)borate / dichloromethane / 40 °C
View Scheme
C35H42AuF6N3

C35H42AuF6N3

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: triethylamine / dichloromethane
2: tris(pentafluorophenyl)borate / dichloromethane / 40 °C
View Scheme
ethyl 2-[(dimethylamino)methylene]-3-oxobutanoate
134653-70-6, 51145-57-4

ethyl 2-[(dimethylamino)methylene]-3-oxobutanoate

Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
Multi-step reaction with 2 steps
1: hydroxylamine hydrochloride / ethanol / -5 - 20 °C
2: triethylamine; 1,1'-carbonyldiimidazole / dichloromethane / 0 °C / Heating
View Scheme
Multi-step reaction with 3 steps
1: hydroxylamine / methanol; water / -5 - 15 °C
2: acetic acid; hydrogenchloride / water / Reflux
3: triethylamine; 1,1'-carbonyldiimidazole / dichloromethane / 0 °C / Heating
View Scheme
Leflunomide
75706-12-6

Leflunomide

teriflunomide

teriflunomide

Conditions
ConditionsYield
With sodium hydroxide In water at 20℃; for 2h; Reagent/catalyst; Temperature;98%
Leflunomide
75706-12-6

Leflunomide

teriflunomide

teriflunomide

Conditions
ConditionsYield
Stage #1: Leflunomide With sodium hydroxide In water; isopropyl alcohol at 30℃; pH=12;
Stage #2: With hydrogenchloride at 30℃;
95%
With sodium hydroxide In methanol; water; butanone at 50℃; for 1h; Concentration; Temperature; Solvent;94%
With water
Leflunomide
75706-12-6

Leflunomide

N,N-dimethyl-formamide dimethyl acetal
4637-24-5

N,N-dimethyl-formamide dimethyl acetal

C12H8F3N2O2(1-)*C4H12N(1+)
132934-77-1

C12H8F3N2O2(1-)*C4H12N(1+)

Conditions
ConditionsYield
In 1,4-dioxane 1) 72 h, r.t. 2) 1 h, 65-75 deg C;60%
Leflunomide
75706-12-6

Leflunomide

C13H11F3N2O5S

C13H11F3N2O5S

Conditions
ConditionsYield
With bis(methanesulfonyl)peroxide at 23℃; for 24h; Inert atmosphere; Schlenk technique;60%
1-(difluoromethoxy)-3-methyl-6-nitro-4-(trifluoromethyl)-1H-benzo[d][1,2,3]triazol-3-ium trifluoromethanesulfonate

1-(difluoromethoxy)-3-methyl-6-nitro-4-(trifluoromethyl)-1H-benzo[d][1,2,3]triazol-3-ium trifluoromethanesulfonate

Leflunomide
75706-12-6

Leflunomide

N-(2-(difluoromethoxy)-4-(trifluoromethyl)phenyl)-5-methylisoxazole-4-carboxamide

N-(2-(difluoromethoxy)-4-(trifluoromethyl)phenyl)-5-methylisoxazole-4-carboxamide

Conditions
ConditionsYield
With 2,2,6,6-Tetramethyl-1-piperidinyloxy free radical; lithium carbonate In 1,2-dichloro-ethane; acetonitrile at 60℃; for 20h; Sealed tube;32%
Leflunomide
75706-12-6

Leflunomide

Conditions
ConditionsYield
With tetra(n-butyl)ammonium hydroxide; 1,2-dichloro-ethane In methanol at 60℃; for 10h; Electrochemical reaction; Green chemistry;31%
allyl iodid

allyl iodid

Leflunomide
75706-12-6

Leflunomide

2-cyano-3-hydroxy-N-(4-trifluoromethylphenyl)-hepta-2,6-dienamide

2-cyano-3-hydroxy-N-(4-trifluoromethylphenyl)-hepta-2,6-dienamide

Conditions
ConditionsYield
With hydrogenchloride; n-butyllithium In tetrahydrofuran; hexane; water; ethyl acetate
Leflunomide
75706-12-6

Leflunomide

Manitimus

Manitimus

lawesson's reagent [2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide]

lawesson's reagent [2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide]

Leflunomide
75706-12-6

Leflunomide

5-methyl-4-(4-trifluoromethylphenyl)aminothiocarbonylisoxazole

5-methyl-4-(4-trifluoromethylphenyl)aminothiocarbonylisoxazole

Conditions
ConditionsYield
In methanol; dichloromethane; toluene
In methanol; dichloromethane; toluene
Leflunomide
75706-12-6

Leflunomide

teriflunomide

teriflunomide

Conditions
ConditionsYield
With hydrogenchloride In water for 24h; pH=1;0.297 g
Leflunomide
75706-12-6

Leflunomide

cyclomaltooctaose
17465-86-0

cyclomaltooctaose

C48H80O40*C12H9F3N2O2

C48H80O40*C12H9F3N2O2

Conditions
ConditionsYield
In water at 21.84℃; under 750.075 Torr;
Leflunomide
75706-12-6

Leflunomide

β‐cyclodextrin
7585-39-9

β‐cyclodextrin

C42H70O35*C12H9F3N2O2

C42H70O35*C12H9F3N2O2

Conditions
ConditionsYield
In water at 21.84℃; under 750.075 Torr;
Leflunomide
75706-12-6

Leflunomide

alpha cyclodextrin
10016-20-3

alpha cyclodextrin

C36H60O30*C12H9F3N2O2

C36H60O30*C12H9F3N2O2

Conditions
ConditionsYield
In water at 21.84℃; under 750.075 Torr;

Leflunomide Specification

The Leflunomide, with the CAS registry number 75706-12-6, is also known as 4-Isoxazolecarboxamide, 5-methyl-N-(4-(trifluoromethyl)phenyl)-; 5-Methylisoxazole-4-carboxylic acid (4-trifluoromethyl)anilide; Arava. It belongs to the product categories of Active Pharmaceutical Ingredients; API; Osteoarthritis and Rheumatoid Arthritis; Inhibitors; Intermediates & Fine Chemicals; Pharmaceuticals; Cytokine signaling; Aromatics; Heterocycles; An immunosuppressive agent. This chemical's molecular formula is C12H9F3N2O2 and molecular weight is 270.21. What's more, its systematic name is 5-Methyl-N-[4-(trifluoromethyl)phenyl]-1,2-oxazole-4-carboxamide. In addition, Leflunomide(CAS 75706-12-6) is off white crystalline solid which should be sealed in the container and stored in the cool and dry place.

Physical properties about Leflunomide are: (1)ACD/LogP:  2.287; (2)# of Rule of 5 Violations:  0; (3)ACD/LogD (pH 5.5):  2.29; (4)ACD/LogD (pH 7.4):  2.29; (5)ACD/BCF (pH 5.5):  32.22; (6)ACD/BCF (pH 7.4):  32.22; (7)ACD/KOC (pH 5.5):  417.95; (8)ACD/KOC (pH 7.4):  417.92; (9)#H bond acceptors:  4; (10)#H bond donors:  1; (11)#Freely Rotating Bonds:  2; (12)Polar Surface Area:  55.13 Å2; (13)Index of Refraction:  1.541; (14)Molar Refractivity:  61.024 cm3; (15)Molar Volume:  194.108 cm3; (16)Polarizability:  24.192×10-24 cm3; (17)Surface Tension:  40.5660018920898 dyne/cm; (18)Density:  1.392 g/cm3; (19)Flash Point:  128.771 °C; (20)Enthalpy of Vaporization:  52.861 kJ/mol; (21)Boiling Point:  289.311 °C at 760 mmHg; (22)Vapour Pressure:  0.0020000000949949 mmHg at 25°C.

Preparation of Leflunomide(CAS 75706-12-6): It can be produced by 5-methyl-isoxazole-4-carbonyl chloride and 4-trifluoromethyl-aniline.  This reaction needs solvent diethyl ether at ambient temperature. The yield is 93%.

Leflunomide can be produced by 5-methyl-isoxazole-4-carbonyl chloride and 4-trifluoromethyl-aniline

Uses of Leflunomide: It is a DMARD which is used in active moderate to severe rheumatoid arthritis and psoriatic arthritis. It is also an immunomodulatory drug inhibiting dihydroorotate dehydrogenase. It can relieve symptoms of rheumatoid arthritis and psoriatic arthritis. What's more, Leflunomide (CAS 75706-12-6) can be used to produce other chemicals. For example, it can react with dimethoxymethyl-dimethyl-amine to get dimethoxymethyl-dimethyl-amine. This reaction needs solvent dioxane. The yield is 60%.

Leflunomide can react with dimethoxymethyl-dimethyl-amine to get dimethoxymethyl-dimethyl-amine

When you are using this chemical, please be cautious about it as the following: Leflunomide (CAS 75706-12-6) is harmful if swallowed. And it is irritating to eyes, respiratory system and skin. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. So people should wear suitable protective clothing when contact it.

You can still convert the following datas of Leflunomide (CAS 75706-12-6) into molecular structure:
(1) SMILES:O=C(Nc1ccc(cc1)C(F)(F)F)c2c(onc2)C
(2) Std. InChI:InChI=1S/C12H9F3N2O2/c1-7-10(6-16-19-7)11(18)17-9-4-2-8(3-5-9)12(13,14)15/h2-6H,1H3,(H,17,18)
(3) Std. InChIKey:VHOGYURTWQBHIL-UHFFFAOYSA-N

The following are the toxicity data of Leflunomide (CAS 75706-12-6) which has been tested.

Organism Test Type Route Reported Dose (Normalized Dose) Effect Source
mouse LD50 intraperitoneal 185mg/kg (185mg/kg)   United States Patent Document. Vol. #5494911,
mouse LD50 oral 445mg/kg (445mg/kg)   United States Patent Document. Vol. #5494911,
rat LD50 intraperitoneal 170mg/kg (170mg/kg)   United States Patent Document. Vol. #5494911,
rat LD50 oral 235mg/kg (235mg/kg)   United States Patent Document. Vol. #5494911,

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