Pyrazole derivatives and process for the production thereof

Abstract

The present invention provides pyrazole derivatives useful as production intermediates for isoxazoline derivatives having an excellent herbicidal effect and selectivity between crops and weeds as well as processes for producing the same. The pyrazole derivatives or pharmaceutically acceptable salts thereof which are inventive compounds are represented by the general formula [I] or a salt thereof: wherein R 1 represents a C1 to C6 alkyl group, R 2 represents a C1 to C3 haloalkyl group, R 3 represents a hydrogen atom, a C1 to C3 alkyl group which may be substituted with one or more substituents selected from the following substituent group α, or a formyl group, R 4 represents a hydrogen atom or a C1 to C3 haloalkyl group, provided that R 4 represents a C1 to C3 haloalkyl group in the case that R 3 is a hydrogen or a formyl group, and R 4 is a hydrogen group or a C1 to C3 haloalkyl group in the case that R 3 is a C1 to C3 alkyl group which may be substituted with one or more substituents selected from the following substituent group α.

1 . A process for producing a pyrazole derivative represented by the general formula [6], comprising a step of reacting a compound represented by the general formula [4] with a compound represented by the general formula [5] in the presence of a base:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, R 6  represents C1 to C3 alkyl group, and L 1  is a leaving group which is more reactive than a halogen atom remaining after haloalkylation and represents a halogen atom, a C1 to C3 alkylsulfonyloxy group, a C1 to C3 haloalkylsulfonyloxy group, a phenylsulfonyloxy group which may be substituted, or a benzylsulfonyloxy group which may be substituted, and the like.  
   
   
       2 . A process for producing a pyrazole derivative represented by the general formula [6], comprising a step of reacting a compound represented by the general formula [4] with triphenylphosphine, a compound represented by the general formula [7], and an azo compound [8]:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, and R 6  represents C1 to C3 alkyl group.  
   
   
       3 . A process for producing a pyrazole derivative represented by the general formula [10], comprising a step of reacting a compound represented by the general formula [9] with a halogenating agent:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, R 7  and R 8  each represents a hydrogen atom or a C1 to C2 alkyl group, and X is a halogen atom.  
   
   
       4 . A process for producing a pyrazole derivative represented by the general formula [12], comprising a step of reacting a compound represented by the general formula [10] with a compound represented by the general formula [11]:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, R 7  and R 8  each represents a hydrogen atom or a C1 to C2 alkyl group, and X is a halogen atom.  
   
   
       5 . The process for producing a pyrazole derivative represented by the general formula [13] according to claim  10 , wherein the compound represented by the general formula [12] according to the above (10) is hydrolyzed.  
   
   
       6 . The process for producing a pyrazole derivative represented by the general formula [13] according to claim  10 , wherein the compound represented by the general formula [10] according to the above (10) is reacted with a sulfide.  
   
   
       7 . A process for producing a pyrazole derivative represented by the general formula [15], comprising a step of formylating a compound represented by the general formula [14]:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group and R 2  represents a C1 to C3 haloalkyl group.  
   
   
       8 . A process for producing a pyrazole derivative represented by the general formula [17], comprising a step of reacting a compound represented by the general formula [16] with a compound represented by the general formula [5] in the presence of a base:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, and L 1  is a leaving group which is more reactive than a halogen atom remaining after haloalkylation and represents a halogen atom, a C1 to C3 alkylsulfonyloxy group, a C1 to C3 haloalkylsulfonyloxy group, a phenylsulfonyloxy group which may be substituted, or a benzylsulfonyloxy group which may be substituted, and the like.  
   
   
       9 . A process for producing a pyrazole derivative represented by the general formula [19], comprising a step of halomethylating a compound represented by the general formula [18]:  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents a C1 to C6 alkyl group, R 2  represents a C1 to C3 haloalkyl group, R 4  represents a hydrogen atom or a C1 to C3 haloalkyl group, and X is a halogen atom.