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

• US 9,840,490 B2
• Filed: 12/23/2016
• Issued: 12/12/2017
• Est. Priority Date: 07/31/2014
• Status: Expired due to Fees

• Current Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Original Assignee: Dow Agrosciences LLC (Corteva, Inc.)
• Inventors: Li, Xiaoyong, Yang, Qiang, Roth, Gary, Lorsbach, Beth
• Primary Examiner(s): Morris, Patricia L
• Application Number:
  US15/389,531
• Publication Number:
  US 20170101393A1
• Time in Patent Office: 354 Days
• Field of Search: 5462754
• 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 commercially available 3-ethoxyacrylonitrile to provide 3-(3-amino-1H-pyrazol-1-yl)pyridine, and by converting the amino group to a chloro group by a Sandmeyer reaction.

Claims

1. A process for preparing diazonium salt (8b)

2. The process of claim 1, wherein the sodium nitrite is used in an excess of about 1.3-fold to about 2-fold.

3. The process of claim 1, wherein the sodium nitrite is added as an aqueous solution.

4. The process of claim 1, wherein the aqueous hydrochloric acid is used in a large excess.

5. The process of the claim 1, wherein the 3-(3-amino-1H-pyrazol-1-yl)pyridine (8a) and aqueous hydrochloric acid are mixed and cooled to about 0°

C.

6. The process of claim 5, wherein an aqueous solution of sodium nitrite is slowly added maintaining the temperature below about 5°

C.

7. The process of claim 6, wherein the step of treating is carried out at about 0°

C. following the addition of the aqueous solution of sodium nitrite.