Process for the preparation of certain triaryl pesticide intermediates
View Patent ↗Certain intermediates useful in the preparation of triaryl pesticides are prepared from a substituted phenyl hydrazine and a substituted benzaldehyde by a cyclization process.
1. A process for preparing triaryl pesticide intermediates of the Formula (I),
wherein
R 1 represents NO 2 or CO 2 R 3 ,
R 2 represents C 1 -C 6 haloalkoxy, and
R 3 represents C 1 -C 6 alkyl
which comprises:
a) contacting a substituted phenyl hydrazine of Formula (II)
wherein
R 2 is as previously defined,
X represents Cl or Br, and
n=0, 1 or 2,
with a substituted benzaldehyde of Formula (III)
wherein
R 1 is as previously defined,
in an inert organic solvent to provide a hydrazone of Formula (IV)
wherein
R 1 and R 2 are as previously defined;
b) chlorinating or brominating the hydrazone of Formula (IV) with a chlorinating or brominating agent in the presence of a sulfide in an inert organic solvent to provide a halohydrazone of Formula (V)
wherein
R 1 and R 2 are as previously defined, and
Y represents Cl or Br; and
c) contacting the halohydrazone of Formula (V) with an amine of formula
R 4 CH 2 NH 2
wherein
R 4 represents H, Si(CH 3 ) 3 or CH(C 6 H 5 ) 2
in the presence of an organic base followed by oxidizing with an oxidizing agent.
2. The process of claim 1 in which R 2 is OCF 3 or OCF 2 CF 3 .
3. The process of claim 1 in which R 3 is CH 3 .
4. The process of claim 1 in which R 4 is Si(CH 3 ) 3 .
5. The process of claim 1 in which the chlorinating or brominating agent is N-chlorosuccinamide or 1,3-dichloro-5,5-dimethyl hydantoin.
6. The process of claim 1 in which the oxidizing agent is NaOCl, Ca(OCl) 2 or Ag 2 (CO 3 ).