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With hydrogenchloride; potassium iodide; sodium nitrite In water at 0 - 20℃; for 4 h; Large scale
The compound N-methyl-3-aminopyrazole (2000 g, 20.6 mol, 1.0 eq) was dissolved in 6000 ml of concentrated hydrochloric acidAnd 2000 ml of water,Cooled to 0-5 ° C in an ice-salt bath,Then, 3.5 L of a saturated aqueous sodium nitrite solution (NaNO2, 2842.8 g, 41.2 mol, 2.0 eq) was added dropwise,After mechanical stirring reaction for 20 min,The reaction solution was added dropwise to an aqueous solution of 8000 ml of potassium iodide (8549.0 g, 51.5 mol, 2.5 eq) at 0 ° C,After completion of the dropwise addition,The reaction was allowed to spontaneously rise to room temperature for 4 h,After TLC detection reaction was complete,Add ethyl acetate extraction 2 times,The organic phase was dried with saturated brine and concentrated,The crude product was purified via flash column to give compound 3-iodo-l-methyl-lH-pyrazole (3473.8 g, 16.7 mol)Yield 81.0percent.
54.4%
With copper(l) iodide; diiodomethane; isopentyl nitrite In tetrahydrofuran for 5 h; Inert atmosphere; Reflux
To a suspension of l-methyH/f-pyrazol-3-amine (200 mg, 2.06 mmol) in THF (5 mL) under 2 atmosphere were added Cul (431 mg, 2.27 mmol) and CH2I2 (0.5 mL, 6.18 mmol), followed by addition of isopentyi nitrite (8.30 mL, 61.78 mmol). The mixture was heated at reflux for 5 hours, then cooled to rt, and diluted with EtOAc (15 mL). The resulted mixture was washed with saturated Na2S203 aqueous solution (15 mL), then filtered through a pad of ('Η . ΠΤ. \ and the filtrate was washed with saturated brine (10 ml,). The organic phase was dried over anhydrous Na2S04 and concentrated in vacuo. The residue was purified by a silica gel column chromatography (PE/EtQAc (v/v) = 10/1) to get the title compound as yellow liquid (233 mg, yield 54.4percent). MS (ESI, pos. ion) m/z: 209.0 [M+H]+.
Reference：
[1] Patent: CN105669733, 2016, A, . Location in patent: Paragraph 0031; 0032; 0033; 0034
[2] Patent: WO2015/175579, 2015, A1, . Location in patent: Paragraph 351
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