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Process for the preparation of 3-(3-chloro-1h-pyrazol-1-yl)pyridine

A technology of pyridine and bromopyridine is applied in the field of improved preparation of 3-pyridine and crystal purification, and can solve the problems of difficult separation of pure substances, difficult preparation and low yield of products.

Inactive Publication Date: 2017-03-08
DOW AGROSCIENCES LLC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The yield of the method disclosed above is low, and the starting material relied on is difficult to prepare (3-chloropyrazole), and the product obtained is difficult to separate in the form of pure substance

Method used

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  • Process for the preparation of 3-(3-chloro-1h-pyrazol-1-yl)pyridine
  • Process for the preparation of 3-(3-chloro-1h-pyrazol-1-yl)pyridine
  • Process for the preparation of 3-(3-chloro-1h-pyrazol-1-yl)pyridine

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[0019] The present invention provides an improved process for the preparation of 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b) by coupling 3-bromopyridine with commercially available 3-aminopyrazole, 3- (3-Amino-1H-pyrazol-1-yl)pyridine (8a) was purified by recrystallization, and the amino group was converted to the chloro group by Sandmeyer reaction.

[0020] In the first step, 3-bromopyridine is mixed with 3-aminopyrazole in a water-miscible polar aprotic organic solvent at a temperature of about 75°C to about 155°C in the presence of a catalytic amount of copper chloride and a base Coupling affords 3-(3-amino-1H-pyrazol-1-yl)pyridine (8a). Although stoichiometric amounts of 3-bromopyridine and 3-aminopyrazole are required, an excess of 3-aminopyrazole is often routinely used. An excess of about 10 mole percent to about 50 mole percent 3-aminopyrazole is preferred. The coupling is performed in the presence of about 5 mol% to about 50 mol% copper chloride, preferably about 15 m...

Embodiment

[0026] 1. Preparation of 3-(3-amino-1H-pyrazol-1-yl)pyridine (8a)

[0027]

[0028] In a four-neck round bottom flask (500mL), charge cuprous (I) chloride (2.51g, 25.3mmol), 1H-pyrazol-3-amine (15.8g, 190mmol), potassium carbonate (35.0g, 253mmol) and N,N-dimethylformamide (100 mL). The mixture was stirred under nitrogen for 10 minutes and 3-bromopyridine (12.2 mL, 127 mmol) was added. The mixture was heated at 110°C for 18 hours at which time HPLC analysis indicated about 15.5% 3-bromopyridine remained. The reaction was allowed to cool to 20 °C and concentrated to give a brown residue. Water (200 mL) was added and the resulting suspension was stirred at 20°C for 2 hours and filtered. The solid was rinsed with water (2 x 50 mL) and dried to give a light green solid. The solid was suspended in water (200 mL), and the resulting suspension was heated at 90 °C for 2 hours, passed through Pad hot filter. Rinse the pad with hot water (50 mL). The combined filtrates were...

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Abstract

3-(3-Chloro-1H-pyrazol-1-yl)pyridine is prepared by coupling 3-bromopyridine with commercially available 3-aminopyrazole, purifying the 3-(3-amino-1H-pyrazol-1-yl)pyridine by crystallization, and converting the amino group to a chloro group by a Sandmeyer reaction.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of the following US Provisional Patent Application Serial No. 62 / 031,557, filed July 31, 2014, the entire contents of which are hereby expressly incorporated by reference into this application. Background technique [0003] The present invention relates to an improved process for the preparation of 3-(3-chloro-1H-pyrazol-1-yl)pyridines. [0004] US 20130288893 (A1 ) describes, inter alia, certain (3-halo-1-(pyridin-3-yl)-1H-pyrazol-4-yl)amides and carbamates and their use as pesticides. A route to this compound involves the preparation of 3-(3-chloro-1H-pyrazol-1-yl)pyridine by direct coupling of 3-bromopyridine with 3-chloropyrazole. 3-Chloropyrazole was prepared by: a) treatment of 1H-pyrazole with 2-dimethylsulfamoyl chloride and sodium hydride to give N,N-dimethyl-1H-pyrazole-1-sulfonamide, b ) treatment of N,N-dimethyl-1H-pyrazole-1-sulfonamide with hexachloroethane and n-butyl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D231/14A01N43/46A61K31/415
CPCC07D401/04A01N43/56A01N43/40
Inventor Q·杨B·洛尔斯巴赫C·迪米西斯A·M·布伊塞小罗纳德·罗斯X·李
Owner DOW AGROSCIENCES LLC
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