Processes for the preparation of pesticidal compounds
View Patent ↗The present application provides processes for making pesticidal compounds and compounds useful both as pesticides and in the making of pesticidal compounds.
1. A process for the selective mono-acylation of 3-chloro-1H-pyrazol-4-amine hydrochloride (1a)
which comprises acylating amine (1a) with acetic anhydride in the presence of a base, to yield amide (1b)
2. The method of claim 1 , wherein the base is an inorganic base.
3. The process of claim 1 , wherein the base is sodium bicarbonate.
4. The process of claim 1 , wherein the acylating is carried out at a temperature of from about 0° C. to about 10° C.
5. The process of claim 4 , wherein the acylating is carried out at a temperature of about 5° C.
6. The process of claim 1 , wherein the base is an inorganic base and the acylating is carried out at a temperature of from about 0° C. to about 10° C.
7. The process of claim 6 , wherein the inorganic base is sodium bicarbonate and the temperature is about 5° C.
8. The process of claim 1 , further comprising halogenating and reducing 4-nitropyrazole
with concentrated hydrochloric acid at a temperature between about 10° C. and about 20° C. with between about 1 equivalent and about 4 equivalents of triethylsilane and about 1 weight percent to about 10 weight percent palladium on alumina to provide 3-chloro-1H-pyrazol-4-amine hydrochloride (1a)
9. The process of claim 8 , wherein the halogenating and reducing is conducted in a polar protic solvent.
10. The process of claim 9 , wherein the polar protic solvent is methanol or ethanol.
11. The process of claim 8 , wherein the triethylsilane is used in an amount of about 2.5 equivalents to about 3.5 equivalents.