5-halo-4-fluoro-4,7,7-trimethyl-3-oxabicyclo[4.1.0]heptan-2-ones, process for their preparation and their use for preparing cyclopropanecarboxylic acids

Abstract

5-Halo-4-fluoro-4,7,7-trimethyl-3-oxabicyclo[4.1.0]heptan-2-ones, process for their preparation and their use for preparing cyclopropanecarboxylic acids Compounds of the formula (I), in which Hal is Cl, Br or I, are suitable for use as intermediates in the preparation of pyrethroids.

1 . A compound of the formula (I),  
       
         
           
           
               
               
           
         
       
       in which Hal is Cl, Br or I.  
     
     
         2 . A compound of the formula (I) as claimed in  claim 1 , in which Hal is Br.  
     
     
         3 . A process for preparing a compound of the formula (I) as claimed in  claim 1 , which comprises reacting an enollactone of the formula (II) with a halofluorinating agent (“HalF”)  
       
         
           
           
               
               
           
         
       
       in which Hal is Cl, Br or I.  
     
     
         4 . A process for preparing a cis-cyclopropane carboxylic acid of  
       
         
           
           
               
               
           
         
       
       which comprises reacting the compound of the formula (I) as claimed in  claim 1  with a reducing agent.  
     
     
         5 . A process for preparing a compound of the formula (VI),  
       
         
           
           
               
               
           
         
       
       in which R is the radical of an alcohol from the pyrethroid group, which comprises the following steps: 
 a) Reaction of an enollactone of the formula (II) with a halofluorinating agent to give a compound of the formula (I) as claimed in  claim 1 ,  
 b) Reaction of the compound of the formula (I) with a reducing agent to give a cyclopropanecarboxylic acid of the formula (IV) as claimed in claim and  
 c) Esterification of cyclopropanecarboxylic acid of the formula (IV) with a compound (V),  
 R—X  (V)  
   
 in which X is a leaving group and R is the radical of an alcohol from the pyrethroid group.