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

摘要

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.

主权项

1. A process for preparing 3-(3-chloro-1H-pyrazol-1-yl)pyridine (5b),which comprises
a) treating 3-hydrazinopyridine.dihydrochloridewith 3-ethoxyacrylonitrilein a (C1-C4) aliphatic alcohol at a temperature of about 25° C. to about 100° C. in the presence of an alkali metal (C1-C4) alkoxide to provide 3-(3-amino-1H-pyrazol-1-yl)pyridine (8a) b) treating the 3-(3-amino-1H-pyrazol-1-yl)pyridine (8a) in aqueous hydrochloric acid with sodium nitrite a temperature of about 0° C. to about 25° C. to provide the diazonium salt (8b)and
c) treating the diazonium salt (8b) with copper chloride a temperature of about 0° C. to about 25° C.