Process for the preparation of 5-fluoro-1H-pyrazoles
View Patent ↗A new process for the preparation of 5-fluoro-1H-pyrazoles of the general formula (I) as described herein comprising reacting an olefin with an hydrazine.
1. A process for the synthesis of a 5-fluoro-1H-pyrazoles of formula (I)
by reacting an olefin of formula (a)
with one or more nucleophiles, and optionally a base,
followed by reacting with one or more hydrazines of formula (b)
R 1 —NH—NH 2 (b),
wherein
R 1 is selected from C 1 -C 6 alkyl, cycloalkyl, or C 5 -C 10 aryl;
R 2 is a trihalomethyl moiety with at least one fluorine atom; and
R 3 is selected from C 1 -C 5 haloalkyl;
and the nucleophile is not water.
2. Process according to claim 1 , wherein the nucleophile is selected from alcohols, thioles or secondary amines, and in case the nucleophile is an alcohol or a thiol, is also in the presence of a base.
3. Process according to claim 1 , wherein
R 1 is methyl,
R 2 is CF 3 , and
R 3 is C 2 F 5 .
4. Process according to claim 1 , wherein the nucleophile is methanol and the base is used and is triethylamine.
5. Process according to claim 1 , wherein R 1 is methyl.
6. Process according to claim 1 , wherein the nucleophile is a thiol.
7. Process according to claim 1 , wherein the nucleophile is a secondary amine.
8. Process according to claim 1 , wherein the nucleophile is an alcohol.
9. Process according to claim 1 , wherein the nucleophile is an alcohol and is used in the presence of the base.
10. Process according to claim 1 , wherein the nucleophile is a thiol and is used in the presence of the base.
11. Process according to claim 1 , wherein R 3 is selected from CF 3 , CF 2 Cl, C 2 F 5 , C 3 F 7 , CF 2 CF 2 Cl, or CFClCF 3 .
12. Process according to claim 1 , wherein R 1 is selected from C 1 -C 6 alkyl.
13. Process according to claim 1 , wherein the nucleophile is one or more of methanol, ethanol, isopropanol, benzylalcohol, methylamine, ethylamine or dimethylamine.
14. Process according to claim 3 , wherein the nucleophile is one or more of methanol, ethanol, isopropanol, benzylalcohol, methylamine, ethylamine or dimethylamine.
15. Process according to claim 3 , wherein the nucleophile is methanol and the base is used and is trimethylamine.