Process for the preparation of 3-(3-chloro-1<i>H</i>-pyrazol-1-yl)pyridine

摘要

This disclosure relates to the field of preparation of 3-(3-chloro-1H-pyrazol-1-yl)pyridine and intermediates therefrom. These intermediates are useful in the preparation of certain pesticides.

主权项

1. A process for preparing 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b)which comprises
a) cyclizing 3-hydrazinopyridine•dihydrochloridewith alkyl methacrylate, wherein R represents (C1-C4) alkyl,in a (C1-C4) alkyl alcohol at a temperature of about 25° C. to about 60° C. in the presence of an alkali metal (C1-C4) 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).