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

• US 9,024,031 B1
• Filed: 10/17/2014
• Issued: 05/05/2015
• Est. Priority Date: 08/19/2014
• Status: Expired due to Fees

• Current Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Original Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Inventors: Lorsbach, Beth, Podhorez, David E., Yang, Qiang
• Primary Examiner(s): Morris, Patricia L
• Application Number:
  US14/517,344
• Time in Patent Office: 200 Days
• Field of Search: 546/275.4
• US Class Current: 546/275.4
• CPC Class Codes: C07D 401/04 directly linked by a ring-member-to-ring-member bond

Abstract

3-(3-chloro-1H-pyrazol-1-yl)pyridine is prepared by cyclizing 3-hydrazinopyridine.dihydrochloride with a dialkyl maleate to provide an alkyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate, by chlorinating to provide an alkyl 3-chloro-1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate, by oxidizing to provide an alkyl 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylate, by converting the ester to the carboxylic acid by hydrolysis to provide 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylic acid hydrochloride, and by removing the carboxylic acid by a decarboxylation reaction.

Claims

1. A process for preparing 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b),

2. The process of claim 1 in which for step a) the dialkyl maleate is diethyl maleate, the (C₁-C₄) aliphatic alcohol is ethanol and the alkali metal (C₁-C₄) alkoxide is sodium ethoxide.

3. The process of claim 1 in which for step b) the chlorinating reagent is phosphoryl chloride and the inert organic solvent is acetonitrile.

4. The process of claim 1 in which for step c) the oxidant is manganese (IV) oxide and the inert organic solvent is acetonitrile.

5. The process of claim 1 in which for step e) the polar aprotic solvent is N,N′

-dimethylformamide.