ChemicalBook CAS DataBase List 1H-INDAZOL-4-AMINE

1H-INDAZOL-4-AMINE synthesis

9synthesis methods

Product Name:1H-INDAZOL-4-AMINE
CAS Number:41748-71-4
Molecular formula:C7H7N3
Molecular Weight:133.15

2942-40-7

41748-71-4

The general procedure for the synthesis of 4-aminoindazole from 4-nitroindazole is as follows: 1. 2-Methyl-3-nitroaniline (2.27 g, 14.91 mmol) was dissolved in acetic acid (60 mL) and an aqueous solution of sodium nitrite (1.13 g, 1.1 eq.) was added (5 mL). After 2 hours of reaction, the dark red solution was poured into ice/water and the precipitate was collected by filtration to give 4-nitro-1H-indazole (1.98 g, 81% yield). 2. 4-Nitro-1H-indazole (760 mg, 4.68 mmol), charcoal-loaded palladium (10%, catalyst), and ethanol (30 mL) were stirred under a hydrogen balloon for 4 hours. Upon completion of the reaction, the solvent was removed in vacuum by filtration through diatomaceous earth to afford 1H-indazol-4-ylamine (631 mg, 100% yield). 3. A suspension of 1H-indazol-4-ylamine (63 mg, 4.74 mmol) in 6 M hydrochloric acid (7.2 mL) was added dropwise to an aqueous solution (2 mL) of sodium nitrite (337 mg, 4.89 mmol) at below 0 °C. After stirring for 30 min, sodium tetrafluoroborate (724 mg) was added. The reaction mixture formed a viscous solution, which was filtered and washed briefly with water to give 1H-indazole-4-diazotetrafluoroborate (218 mg, 20% yield) as a dark red solid. 4. Dry methanol (4 mL) was purged with argon for 5 min and 1H-indazole-4-diazotetrafluoroborate (218 mg, 0.94 mmol), bis(pinacolato)diboron (239 mg, 1.0 eq.), and [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) chloride (20 mg) were added. The reaction mixture was stirred for 5 hours and then filtered through diatomaceous earth. The residue was purified by fast chromatography to afford the target product 4-aminoindazole (117 mg).

2942-40-7 Synthesis

2942-40-7
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41748-71-4
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$19.00/250mg

Yield: 100%

Reaction Conditions:

with hydrogen;palladium 10% on activated carbon in ethanol for 4 h;

Steps:

5
Reference Example 5: Indazole-4-Boronate Ester (70): Route 1 EPO (70) (69)To a solution of 2-methyl-3-nitroaniline (2.27g, 14.91mmol) in acetic acid (6OmL) was added a solution of sodium nitrite (1.13g, 1.1 eq.) in water (5mL). After 2 h, the deep red solution was poured onto ice/ water and the resulting precipitate collected by filtration to yield 4-nitro-lH-indazole (67) (1.98g, 81%).A mixture of 4-nitro-lH-indazole (760mg, 4.68mmol), palladium on charcoal (10%, cat.) and ethanol (3OmL) was stirred under a balloon of hydrogen for 4 h. The reaction mixture was then filtered through celite, and the solvent removed in vacuo to yield lH-indazol-4-ylamine (68) (63 lmg, 100%).An aqueous solution of sodium nitrite (337mg, 4.89mmol) in water (2mL) was added dropwise to a suspension of lH-indazol-4-ylamine (63 lmg, 4.74mmol) in 6M hydrochloric acid (7.2mL) at below O⁰C. After stirring for 30 minutes, sodium tetrafluorobrate (724mg) was added to the reaction mixture. A viscous solution resulted, which was filtered and washed briefly with water to yield lH-indazole-4- diazonium tetrafluoroborate salt (69) (218mg, 20%) as a deep red solid.Dry MeOH (4mL) was purged with argon for 5 minutes. To this was added lH-indazole-4-diazonium tetrafluoroborate salt (218mg, 0.94mmol), bis-pinacolato EPO diboron (239mg, l.Oeq.) and [l,r-bis(diphenylphosphino)ferrocene]palladium (II) chloride (20mg). The reaction mixture was stirred for 5 h and then filtered through celite. The residue was purified using flash chromatography to yield the desired title compound (70), (117mg).

References:

PIRAMED LIMITED WO2006/46031, 2006, A1 Location in patent:Page/Page column 31-33