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

Patent metadata

Field	Value
Publication number	US-9115115-B1
Application number	US-201514666812-A
Country	US
Kind code	B1
Filing date	Mar 24, 2015
Priority date	Aug 19, 2014
Publication date	Aug 25, 2015
Grant date	Aug 25, 2015

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.

First claim

What is claimed is:

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

which comprises
a) treating 3-hydrazinopyridine•dihydrochloride

with a dialkyl maleate

wherein
R represents (C 1 -C 4 ) alkyl,

in a (C 1 -C 4 ) aliphatic alcohol at a temperature of about 25° C. to about 100° C. in the presence of an alkali metal (C 1 -C 4 ) alkoxide to provide an alkyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate (10a)

wherein R is as previously defined;
b) treating the alkyl 5-oxo-2-(pyridin-3-yl)pyrazolidine-3-carboxylate (10a) with a chlorinating reagent in an inert organic solvent at a temperature of about 25° C. to about 100° C. to provide an alkyl 3-chloro-1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate (10b)

wherein R is as previously defined;
c) treating the alkyl 3-chloro-1-(pyridin-3-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate (10b) with an oxidant in an inert organic solvent at a temperature of about 25° C. to about 100° C. to provide an alkyl 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylate (10c)

wherein R is as previously defined;
d) treating the alkyl 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylate (10c) with aqueous hydrochloric acid at a temperature of about 25° C. to about 100° C. to provide 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylic acid hydrochloride (10d)

and
e) treating 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-5-carboxylic acid hydrochloride with copper(II) oxide in a polar aprotic solvent at a temperature of about 80° C. to about 140° C.

2. The process of claim 1 in which for step a) the dialkyl maleate is diethyl maleate, the (C 1 -C 4 ) aliphatic alcohol is ethanol and the alkali metal (C 1 -C 4 ) 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.

6. A molecule having the following structure,

wherein
R represents (C 1 -C 4 ) alkyl.

7. A molecule having the following structure,

wherein
R represents (C 1 -C 4 ) alkyl.

Assignees

• Dow Agrosciences Llc

Inventors

• Yang Qiang
• Lorsbach Beth
• Podhorez David E

Classifications

• C07D401/04 Primary

  directly linked by a ring-member-to-ring-member bond · CPC title