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

• US 9,809,570 B2
• Filed: 10/27/2016
• Issued: 11/07/2017
• Est. Priority Date: 08/19/2014
• Status: Active Grant

• 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:
  US15/335,809
• Publication Number:
  US 20170044134A1
• Time in Patent Office: 376 Days
• Field of Search: 5462761
• 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 3-chloro-1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate (10b)

2. The process of claim 1, wherein the chlorinating reagent is phosphoryl chloride or phosphorus pentachloride.

3. The process of claim 1, wherein the chlorinating reagent is phosphoryl chloride.

4. The process of claim 1, wherein the amount of chlorinating reagent is about a 1.1 fold to about a 10 fold excess.

5. The process of claim 1, wherein the step of treating is performed in an inert organic solvent that is inert to the chlorinating reagent.

6. The process of claim 1, wherein the inert organic solvent is a nitrile solvent.

7. The process of claim 6, wherein the nitrile solvent is acetonitrile.

8. The process of claim 1, wherein the chlorinating reagent is phosphoryl chloride and the inert organic solvent is acetonitrile.

9. The process of claim 1, further comprising neutralizing with a base.

10. The process of claim 9, wherein the base is added in an amount sufficient to adjust the pH to about 8.

11. The process of claim 10, wherein the base is sodium carbonate.

12. The process of claim 1, wherein the step of treating is carried out at a temperature.

13. The process of claim 1, wherein the chlorinating reagent is phosphoryl chloride used in about a 1.1 fold to about a 10 fold excess, the inert organic solvent is acetonitrile, and the step of treating is carried out at a temperature of about 60°

C.