Process for the preparation of phenyl substituted 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid N-methoxy-[1-methyl-2 phenylethyl] amides
View Patent ↗The invention relates to a process for the preparation of a compound of formula (I), wherein R 1 , R 2 and R 3 are as defined in claim 1 , which process comprises a) adding a compound of formula (II), in the presence of an inert organic solvent to a mixture comprising an organic nitrite of formula (III) (R 4 —O—N═O (III)), wherein R 4 is C 1 -C 8 alkyl, a compound of formula (IV), and an inert organic solvent; b) reacting the resulting compound of formula (V), with H 2 N—O—CH 3 to the compound of formula (VII), c) reducing the compound of formula (VII) to the compound of formula (VIII), d) and reacting the compound of formula VIII with a compound of formula (IX), in which R* is halogen, hydroxy or C 1-6 alkoxy, to the compound of formula (I).
1. A process for the preparation of the compound of formula I
wherein
R 1 is hydrogen, halogen or C 1 -C 6 alkyl;
R 2 is hydrogen, halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 6 alkinyl, C 3 -C 6 cycloalkyl-C 3 -C 6 alkinyl, halophenoxy, halophenyl-C 3 -C 6 alkinyl, C(C 1 -C 4 alkyl)=NO—C 1 -C 4 alkyl, C 1 -C 6 haloalkyl, C 1 -C 6 haloalkoxy, C 2 -C 6 haloalkenyl or C 2 -C 6 haloalkenyloxy; and
R 3 is hydrogen, halogen or C 1 -C 6 alkyl;
which process comprises
a) adding a compound of formula II
wherein R 1 , R 2 and R 3 have the meanings as described under formula I, in the presence of an inert organic solvent to a mixture comprising an organic nitrite of formula III
R 4 —O—N═O (III),
wherein R 4 is C 1 -C 8 alkyl, a compound of formula IV
and an inert organic solvent;
b) reacting the resulting compound of formula V
wherein R 1 , R 2 and R 3 have the meanings as described under formula I with O-methyl-hydroxylamine of formula VI
H 2 N—O—CH 3 (VI),
to the compound of formula VII
wherein R 1 , R 2 and R 3 have the meanings as described under formula I;
c) reducing the compound of formula VII to the compound of formula VIII
wherein R 1 , R 2 and R 3 have the meanings as described under formula I
d) and reacting the compound of formula VIII with a compound of formula IX
in which R* is halogen, hydroxy or C 1-6 alkoxy to the compound of formula I.
2. A process according to claim 1 for the preparation of a compound of formula I, wherein at least one of R 1 , R 2 and R 3 is different from hydrogen.
3. A process according to claim 1 for the preparation of a compound of formula I, wherein at least one of R 1 , R 2 and R 3 is halogen.
4. A process according to claim 1 for the preparation of a compound of formula I, wherein R 1 , R 2 and R 3 are chloro.
5. A process according to claim 1 for the preparation of a compound of formula I, wherein R is C 4 -C 7 alkyl.