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Synthetic method for 3, 5-dibromo-4-iodopyridine catalyzed by alkyl silicon reagent

A technology of iodine pyridine and silicon reagent, applied in the synthesis field of halopyridine, can solve the problems of large steric hindrance at the 4-position of tribromopyridine, low reactivity of bromopyridine, difficult separation and purification, etc. Economic and social benefits, easy purification, high reaction yield

Inactive Publication Date: 2013-02-06
XIHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

3,5-dibromo-4-iodopyridine is relatively difficult to synthesize, and there are few reports on the synthesis of 3,5-dibromo-4-iodopyridine at home and abroad, only literature (Chemistry--A European Journalvol. 17; nb. 47; 2011; p. 13284 - 13297) disclosed its synthesis method: using 3,5-dibromopyridine as raw material, tetrahydrofuran and n-hexane as solvent, and n-butyl Lithium base and tetramethylethylenediamine zinc dichloride react to generate active carbanion intermediates, which react with iodine at room temperature to generate 3,5-dibromo-4-iodopyridine, and react The yield was only 8% (22% 3,5-dibromo-2-iodopyridine isomer was generated), and the isomer 3,5-dibromo-2-iodopyridine appeared in the product, making separation, Difficult to purify
We think that the possible reason is that the reactivity of bromopyridine in this kind of direct halogen exchange reaction is not high, and the steric hindrance at the 4-position of 3,4,5-tribromopyridine is relatively large

Method used

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  • Synthetic method for 3, 5-dibromo-4-iodopyridine catalyzed by alkyl silicon reagent
  • Synthetic method for 3, 5-dibromo-4-iodopyridine catalyzed by alkyl silicon reagent
  • Synthetic method for 3, 5-dibromo-4-iodopyridine catalyzed by alkyl silicon reagent

Examples

Experimental program
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Embodiment 1

[0024]

[0025] Synthesis of 3,5-dibromo-4-hydroxypyridine: add solvent carbon tetrachloride 900ml, 4-hydroxypyridine 95.10g (1.0mol), azobisisobutyronitrile (AIBN) to a 2000ml three-necked flask in sequence 0.82g, add 391.56g (2.2mol) of N-bromosuccinimide (NBS) in batches at 20°C, and react at room temperature for 24 hours. The raw material 4-hydroxypyridine and the intermediate 3- After the bromo-4-hydroxypyridine was converted into the target product 3,5-dibromo-4-hydroxypyridine, the reaction was stopped. Post-reaction treatment: After stirring the reaction liquid to cool to room temperature, pour it into 1000ml carbon tetrachloride, stir, filter, wash the filter cake 3 times with 3*300ml carbon tetrachloride, and wash the filtrate once with aqueous sodium bicarbonate solution. Saturated brine was washed once, and the solvent carbon tetrachloride was removed by rotary evaporation to obtain a crude product of 3,5-dibromo-4-hydroxypyridine, which was recrystallized from ...

Embodiment 2

[0028] In a 2000ml three-necked reaction flask, under the protection of nitrogen, add 800ml of anhydrous propionitrile, 124.5g of potassium iodide (0.75mol, 1.5eq), and 59.8g of trimethylchlorosilane (0.55mol, 1.1eq) in sequence And 157.9g (0.50mol, 1.3eq) of the 3,4,5-tribromopyridine intermediate prepared according to the method in Example 1, heated to reflux for 6 hours, and monitored by high performance liquid chromatography. Cool the bath to 0°C, pour the reaction solution into 1000ml of ice, adjust the pH to 7.0 with solid sodium hydroxide, add the extractant 3*600ml of ethyl acetate, extract 3 times, separate the phases, and wash the organic phase with saturated brine Once, separate the phases, dry over anhydrous sodium sulfate, filter, remove the solvent under reduced pressure, and recrystallize with petroleum ether to obtain 156.2 g of pure white 3,5-dibromo-4-iodopyridine, with a yield of 86.1%. 98.7%.

Embodiment 3

[0030] In the reaction, 37.9 g (0.35 mol, 0.7 eq) of trimethylchlorosilane was used, and the other operations were the same as in Example 2.

[0031] According to the operation in Example 2, 131.0 g of pure white 3,5-dibromo-4-iodopyridine was obtained, with a yield of 72.2% and a content of 97.1%.

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Abstract

The invention discloses a synthetic method for halogenated pyridine 3, 5-dibromo-4-iodopyridine. 3, 4, 5-pyridinium tribromide, an alkyl silicon reagent and iodized salt are used as starting materials, and a halogen exchange reaction is performed to generate 3, 5-dibromo-4-iodopyridine in one step. Compared with synthetic methods for the 3, 5-dibromo-4-iodopyridine in prior art, the synthetic method has the advantages that the yield is high, the reaction selectivity is good, the purification is easy, and the like.

Description

technical field [0001] The present invention relates to a synthetic method of halogenated pyridine, especially a synthetic method of 3,5-dibromo-4-iodopyridine. Background technique [0002] Halopyridines are important fine chemical intermediates and are widely used in the fields of medicine and pesticides. Halogenated pyridines containing bromine and iodine are widely used in the fields of pesticides, medicines, and functional materials. 3,5-dibromo-4-iodopyridine is relatively difficult to synthesize, and there are few reports on the synthesis of 3,5-dibromo-4-iodopyridine at home and abroad, only literature ( Chemistry--A European Journalvolume . 17; nb. 47; 2011; p. 13284 - 13297) disclosed its synthesis method: using 3,5-dibromopyridine as raw material, tetrahydrofuran and n-hexane as solvents, and n-butyllithium and Tetramethylethylenediamine zinc dichloride reacts to generate a lively carbanion intermediate, which reacts with iodine at room temperature to generate...

Claims

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Application Information

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IPC IPC(8): C07D213/61
Inventor 杨维清马梦林张园园胡伟发
Owner XIHUA UNIV
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