ChemicalBook CAS DataBase List 5-Iodo-1H-indazole

5-Iodo-1H-indazole synthesis

5synthesis methods

Product Name:5-Iodo-1H-indazole
CAS Number:55919-82-9
Molecular formula:C7H5IN2
Molecular Weight:244.03

19335-11-6

55919-82-9

General procedure for the synthesis of 5-iodo-1H-indazole from 5-aminoindazole: 1. a solution of sodium nitrite (2.7 g, 39.1 mmol) in water (40 ml) was slowly added dropwise to a solution of 1-H-indazol-5-amine (5.2 g, 39.1 mmol) in 6 at 0 °C. 2. N hydrochloric acid (73.7 ml) was added to the above mixture at 0°C. 3. the resulting mixture was added slowly and dropwise to a solution of potassium iodide (26.9 g, 162 mmol) in water (60 ml) at 0 °C. 4. The reaction mixture was stirred at room temperature for 3 hours. 5. After completion of the reaction, the reaction mixture was extracted with ethyl acetate (4 x 30 ml). 6. The organic phases were combined and washed sequentially with 10% w/v sodium thiosulfate solution (4 x 30 ml) and brine (2 x 30 ml). 7. The organic phase was dried with anhydrous magnesium sulfate and then concentrated to give a brown solid product. 8. Yield: 8.64 g (90% of theoretical). 9. 9. The structure of the product was confirmed by 3C-NMR (101 MHz, CDCl3, δppm): 84.4, 111.7, 125.6, 129.9, 133.4, 135.4, 139.0.

19335-11-6
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$10.00/1 g

55919-82-9
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$6.00/1g

Yield:55919-82-9 100%

Reaction Conditions:

Stage #1:1H-indazol-5-ylamine with hydrogenchloride;sodium nitrite in water at -5 - 2; for 1.25 h;
Stage #2: with potassium iodide in water at 90; for 1.75 h;

Steps:

1
SYNTHETIC PREPARATION 15-Aminoindazole (64.73 g, 486.13 mmol) was suspended in 600 mL water and ca. 600 mL ice, and cone. HCI ( 200 mL, 5759 mmol) was added. The mixture was cooled in an ice-salt bath to ca. -5 ⁰C. To this mixture was added, dropwise, a solution of sodium nitrite (37.34 g, 541.2 mmol) in 200 mL water (took about 1 hr). The internal temperature was kept below ca. +2 ⁰C. The resulting brown solution was stirred for a further 15 min at -5 ⁰C, then a solution of potassium iodide (97 g, 584.34 mmol) in 250 mL water was slowly added dropwise (took about 30 min). After complete addition, the reaction was heated to 90 ⁰C for 1.5 hr. After allowing to cool, the solution was filtered to give a fine black solid and the filtrate was allowed to sit overnight in the refrigerator. The next day the filtrate was filtered again and the two solids were combined and dried to give 5-iodoindazole (126.63 g, 106%).

References:

BAYER SCHERING PHARMA AKTIENGESELLSCHAFT WO2008/71451, 2008, A1 Location in patent:Page/Page column 47

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