Process for the preparation of 5-fluoro-1
View Patent ↗A new process for the preparation of 5-fluoro-1H-pyrazoles of the general formula (I) is described, resulting from the reaction of an olefin of the general formula (II) with hydrazines of the formula (III) R 1 —NH—NH 2 (III), wherein R 1 is selected from C 1 -C 6 alkyl, 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, CF 3 , C 2 F 5 , C 3 F 7 , CF 2 CF 2 Cl, CFClCF 3 , in the presence of water and a base.
1. A process for synthesis of 5-fluoro-1H-pyrazole of formula (I)
comprising reacting an olefin of formula (II)
with a hydrazine of formula (III)
R 1 —NH—NH 2 (III),
wherein
R 1 is selected from C 1 -C 6 alkyl;
R 2 is a trihalomethyl moiety with at least one fluorine atom; and
R 3 is selected from C 1 -C 5 haloalkyl,
in the presence of water and a base.
2. A process according to claim 1 , wherein
R 1 is methyl,
R 2 is CF 3 , and
R 3 is C 2 F 5 .
3. A process according to claim 1 , wherein the base is triethylamine.
4. A process according to claim 1 , wherein
R 2 is CF 3 and
R 3 is C 2 F 5 .