Process for preparing homophthalate derivatives

Abstract

The present invention provides a process for the preparation of homophthlate esters useful in the preparation of homophthalic anhydride reactants.

1 . A process for the preparation of homophthalate derivatives of the formula:  
       
         
           
           
               
               
           
         
       
       wherein W is a carboxy protecting group and R 9  and R 10  are independently C 1 -C 6  alkyl or C 1 -C 6  alkoxy; comprising reacting a halobenzene derivative of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 9  and R 10  are as defined above, and R 13  is a halogen, sulfonate ester, tosylate or triflate, with a strong base and a malonate ester of the formula:  
       
         
           
           
               
               
           
         
       
       wherein W is as defined above, in a solvent, wherein said homophthalate derivative of the formula:  
       
         
           
           
               
               
           
         
       
       is produced in a molar ratio of at least about 7.0:3.0 in comparison to the homophthalate derivative of the formula:  
       
         
           
           
               
               
           
         
       
       wherein W, R 9  and R 10  are as defined above.  
     
     
         2 . The process of  claim 1 , wherein said homophthalate derivative of the formula:  
       
         
           
           
               
               
           
         
       
       is produced substantially free of said homophthalate derivative of the formula:  
       
         
           
           
               
               
           
         
       
     
     
         3 . The process of  claim 1 , wherein said strong base is lithium diisopropylamide or lithium tetramethylpiperidide.  
     
     
         4 . The process of  claim 1 , wherein said solvent is tetrahydrofuran.  
     
     
         5 . The process of  claim 1 , wherein W is methyl or ethyl.  
     
     
         6 . The process of  claim 1 , wherein R 13  is selected from the group consisting of chloro, bromo and fluoro.  
     
     
         7 . The process of  claim 1 , wherein R 13  is bromo.  
     
     
         8 . The process of  claim 1 , further comprising removal of the carboxy protecting groups W to form the homophthalic acid derivative of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 9  and R 10  are as defined above.  
     
     
         9 . The process of  claim 8 , further comprising dehydration of said homophthalic acid derivative to form the homophthalic anhydride of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 9  and R 10  are as defined above.