Chemical Process

Abstract

The present invention provides a process for the preparation of a compound of formula (I); wherein X is halogen; Y is ZR 1 ; Z is oxygen or sulphur; and R 1 is C 1-6 alkyl, C 1-6 haloalkyl or C 3-7 cloalkyl; the process comprising either: hydrogenating a compound of formula (II); with a suitable transition metal catalyst in a C 1-6 aliphatic alcohol, an ether, an hydrocarbon as solvent; or, conducting a one-pot hydrogenation of a compound of formula (III): wherein R 2 is phenyl optionally substituted by chloro, C 1-6 alkyl, C 1-6 alkoxy or (C 1-6 alkyl) 2 N; firstly at about 20° C. to form a compound of formula (IV): and then at about 40° C.; both steps (I) and (ii) being carried out in the presence of a suitable catalyst and in the presence of a suitable solvent.

1 . A process for the preparation of a compound of formula (I): 
       
         
           
           
               
               
           
         
       
       wherein
 X is halogen; 
 Y is ZR 1 ; 
 Z is oxygen or sulphur; and 
 R 1  is C 1-6  alkyl, C 1-6  haloalkyl or C 3-7  cycloalkyl; 
 the process comprising either:
 hydrogenating a compound of formula (II): 
 
 
       
         
           
           
               
               
           
         
         
            with a suitable transition metal catalyst in a C 1-6  aliphatic alcohol, an ether, an ester or a hydrocarbon as solvent; or, 
           conducting a one-pot hydrogenation of a compound of formula (III): 
         
       
       
         
           
           
               
               
           
         
         
            wherein R 2  is phenyl optionally substituted by chloro, C 1-6  alkyl, C 1-6  alkoxy or (C 1-6  alkyl) 2 N;
 (i) firstly at about 20° C. to form a compound of formula (IV): 
 
         
       
       
         
           
           
               
               
           
         
         
           
             (ii) and then at about 40° C.; 
              both steps (i) and (ii) being carried out in the presence of a suitable catalyst and in the presence of a suitable solvent. 
           
         
       
     
     
         2 . A process as claimed in  claim 1  wherein X is chloro. 
     
     
         3 . A process as claimed in  claim 1  wherein Z is sulphur. 
     
     
         4 . A process as claimed in  claim 1 , wherein R 1  is C 1-4  alkyl or C 1-4  haloalkyl. 
     
     
         5 . A process as claimed in  claim 1 , wherein Y is ZR 1 ; Z is sulphur; and R 1  is n-propyl. 
     
     
         6 . A process as claimed in  claim 1  wherein the transition metal catalyst for the hydrogenation of a compound of formula (II) is selected from platinum, palladium and a combination of platinum with a transition metal selected from vanadium, iron and manganese. 
     
     
         7 . A process as claimed  claim 6  wherein the transition metal catalyst is on a carbon support. 
     
     
         8 . A process as claimed in  claim 1  wherein the solvent for the hydrogenation of a compound of formula (II) is a C 1-6  aliphatic alcohol, an ether, an ester or a hydrocarbon solvent. 
     
     
         9 . A process as claimed in  claim 1  wherein the hydrogenation of a compound of formula (II) is conducted at a temperature in the range 10 to 90° C. 
     
     
         10 . A process as claimed in  claim 9  wherein the hydrogenation of a compound of formula (II) is conducted at a temperature in the range 20 to 40° C. 
     
     
         11 . A process as claimed in  claim 1  wherein the hydrogenation of a compound of formula (II) is conducted at a pressure of 1 to 10 bar. 
     
     
         12 . A process as claimed in  claim 10  wherein the hydrogenation of a compound of formula (II) is conducted at a pressure of 2 to 4 bar. 
     
     
         13 . A process as claimed in  claim 1  for the preparation of a compound of formula (I) in which X is chloro, Y is ZR 1 ; Z is sulphur; and R 1  is n-propyl; the process comprising hydrogenating a compound of formula (II) in solvent comprising an ether at a pressure of 2 to 4 bar, a temperature in the range 20 to 40° C. and a Pt/V/C catalyst. 
     
     
         14 . A process as claimed in  claim 1  wherein the catalyst for the one-pot hydrogenation is selected from platinum and a mixture of platinum and vanadium. 
     
     
         15 . A process as claimed in  claim 13  wherein the catalyst for the one-pot hydrogenation is selected from platinum on carbon 5-15% w/w; platinum 2-10% w/w and vanadium 0.2-3% w/w on carbon. 
     
     
         16 . A process as claimed in  claim 12 , wherein the solvent for the one-pot hydrogenation is selected from a C 1-6  aliphatic alcohol, an ester, an ether, a hydrocarbon and a ketone. 
     
     
         17 . A process as claimed in  claim 13 , wherein the hydrogenation of a compound of formula (III) or (IV) is conducted at a pressure of 2 to 4 bar. 
     
     
         18 . A process as claimed in  claim 1  for the preparation of a compound of formula (I) in which X is chloro, Y is ZR 1 ; Z is sulphur; and R 1  is n-propyl; the process comprising a one-pot hydrogenation of a compound of formula (III) wherein the hydrogenation is conducted in a solvent of ethyl acetate at a pressure of 2 to 4 bar and using a Pt/C catalyst. 
     
     
         19 . A process as claimed in  claim 1  wherein:
 X is chloro; 
 Z is sulphur; 
 R 1  is n-propyl; 
 the transition metal catalyst for the hydrogenation of a compound of formula (II) is selected from platinum, palladium and a combination of platinum with a transition metal selected from vanadium, iron and manganese; and 
 the solvent for the hydrogenation of a compound of formula (II) is a C 1-6  aliphatic alcohol, an ether, an ester or a hydrocarbon solvent; 
 
     
     
         20 . A process as claimed in  claim 19  wherein:
 the hydrogenation of the compound of formula (II) is conducted at a temperature in the range 20 to 40° C.; 
 the hydrogenation of the compound of formula (II) is conducted at a pressure of 2 to 4 bar; 
 the catalyst for the one-pot hydrogenation is selected from platinum on carbon 5-15% w/w, platinum 2-10% w/w and vanadium 0.2-3% w/w on carbon; and 
 the hydrogenation of the compound of formula (III) or (IV) is conducted at a pressure of 2 to 4 bar.