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

• US 9,522,900 B2
• Filed: 07/28/2015
• Issued: 12/20/2016
• 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: Yang, Qiang, Lorsbach, Beth, Podhorez, David E.
• Primary Examiner(s): Morris, Patricia L
• Application Number:
  US14/811,246
• Publication Number:
  US 20160052908A1
• Time in Patent Office: 511 Days
• Field of Search: 546/276.1
• US Class Current: 1/1
• 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 an alkyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate (10a)

2. The process of claim 1, wherein the amount of dialkyl maleate is a stoichiometric amount.

3. The process of claim 1, wherein the amount of dialkyl maleate is about a 1.5 fold to about a 2 fold excess.

4. The process of claim 1, wherein the amount of alkali metal (C₁-C₄) alkoxide is about a 2 fold to about a 5 fold excess.

5. The process of claim 1, wherein the (C₁-C₄) aliphatic alcohol is ethanol.

6. The process of claim 1, wherein R is ethyl.

7. The process of claim 1, wherein the alkali metal (C₁-C₄) alkoxide is sodium ethoxide.

8. The process of claim 1, wherein the (C₁-C₄) aliphatic alcohol is ethanol, R is ethyl and the alkali metal (C₁-C₄) alkoxide is sodium ethoxide.