Patent ID: 9085552
Filing Date: 2015-07-21
Classification: C07D

Abstract:
1. A process for preparing 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b) which comprises a) cyclizing 3-hydrazinopyridine•dihydrochloride with alkyl methacrylate, wherein R represents (C in a (C 1 -C 4 ) alkyl alcohol at a temperature of about 25° C. to about 60° C. in the presence of an alkali metal (C 1 -C 4 ) alkoxide to provide 4-methyl-1-(pyridin-3-yl)pyrazolidin-3-one (1) b) chlorinating 4-methyl-1-(pyridin-3-yl)pyrazolidin-3-one (1) with a chlorinating reagent in an organic solvent at a temperature of about 25° C. to about 100° C. to provide 3-(3-chloro-4-methyl-4,5-dihydro-1H-pyrazol-1-yl)pyridine (2) c) oxidizing 3-(3-chloro-4-methyl-4,5-dihydro-1H-pyrazol-1-yl)pyridine (2) with an oxidant in a solvent at a temperature of about 25° C. to about 100° C. to provide 3-(3-chloro-4-methyl-1H-pyrazol-1-yl)pyridine (3) d) further oxidizing 3-(3-chloro-4-methyl-1H-pyrazol-1-yl)pyridine (3) with an oxidant in a polar protic solvent at a temperature of about 50° C. to about 100° C. to provide 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-4-carboxylic acid (4) and e) decarboxylating 3-chloro-1-(pyridin-3-yl)-1H-pyrazole-4-carboxylic acid (4) with copper oxide in a polar aprotic solvent at a temperature of about 80° C. to about 180° C. to provide 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b).