Process for the preparation of strobilurin intermediates

Abstract

The present invention relates to a novel improved process and intermediates for the process of preparing the oxime intermediates of formula (II) wherein R 1 is hydrogen, fluoro or chloro, and R 2 is methyl, ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano, fluoro, chloro or bromo. The novel process comprises diazotizing an aniline of formula (VI) reacting the resulting diazonium salt with isopropenylacetate of formula (X) and reacting the resulting ketone of formula (XI) with an organic nitrite in the presence of hydrogene chloride, and methylating the resulting ketooxime of formula (VIII) with a methylating agent and reacting the resulting O-methyl ketooxime of formula (IX) with hydroxylamine. The compounds of formula (II) are intermediates for highly active fungicides from the class of the atrobilurins.

What is claimed is:  
     
         1 . A process for preparing the oximes of formula II  
       
         
           
           
               
               
           
         
       
       wherein 
 R 1  is hydrogen, fluoro or chloro, and  
 R 2  is methyl, ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano, fluoro, chloro or bromo,  
 which process comprises diazotizing an aniline of formula VI  
                     
 reacting the resulting diazonium salt with isopropenylacetate of formula X  
                     
 and reacting the resulting ketone of formula XI  
                     
 with an organic nitrite in the presence of hydrogene chloride, and and methylating the resulting ketooxime of formula VIII  
                     
 with an methylating agent and reacting the resulting O-methyl ketooxime of formula IX  
                     
 with hydroxylamine.  
 
     
     
         2 . The compound 2,4-difluorophenylacetone  
       
         
           
           
               
               
           
         
       
     
     
         3 . A process for preparing the oximes of formula II  
       
         
           
           
               
               
           
         
       
       wherein 
 R 1  is hydrogen, fluoro or chloro, and  
 R 2  is methyl, ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano, fluoro, chloro or bromo,  
 which process comprises diazotizing an aniline of formula VI  
                     
 and reacting the resulting diazonium salt with methylglyoxal-1-oxime of formula VII  
                     
 and methylating the resulting ketooxime of formula VIII  
                     
 with an methylating agent and reacting the resulting O-methyl ketooxime of formula IX  
                     
 with hydroxylamine.  
 
     
     
         4 . A process for preparing the oximes of formula II  
       
         
           
           
               
               
           
         
       
       wherein 
 R 1  is hydrogen, fluoro or chloro, and  
 R 2  is methyl, ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano, fluoro, chloro or bromo,  
 which process comprises reacting a propiophenone of formula IV  
                     
 wherein R 1  and R 2  are as defined for formula II in the presence of hydrochloric acid with an organic nitrite such as pentylnitrite, and converting the resulting ketooxime of formula V  
                     
 wherein R 1  and R 2  are as defined for formula II, into the compound of formula II by reacting it with an aqueous solution of O-methyl-hydroxylamine-hydrochloride, and subsequent isomerisation of the racemate of compound II into predominantly the E-form thereof.  
 
     
     
         5 . A compound of formula II obtained by the process of any one of claims  1 ,  3  or  4 .  
     
     
         6 . Use of the compounds of formula II according to  claim 5  for preparing fungicidal strobilurins of formula I  
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are as defined for formula II in  claim 1  and X is NH or oxygen wherein the compound of formula II in a conventional etherification step is in the presence of a base with the coupled with a compound of formula III  
       
         
           
           
               
               
           
         
       
       wherein X is as defined for formula I and Hal is halogen, preferably chlorine or bromine.