Patent ID: 9115115
Filing Date: 2015-08-25
Classification: C07D

Abstract:
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 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.