Process for preparing zolpidem

Abstract

The invention relates to a process for preparing a compound of formula (I) wherein a compound of formula (II), wherein R 1 denotes chlorine, bromine, iodine, —O—COCH 3 , tosylate or mesylate, is reacted with a compound of formula (III), optionally in a suitable diluent and/or in the presence of a suitable added reagent or catalyst, the reaction being carried out in a temperature range from 20 to 80° C.

What is claimed is:  
     
         1 . A process for preparing a compound of formula (I)  
       
         
           
           
               
               
           
         
       
       wherein 
 a compound of formula (II)  
                     
 wherein  
 R 1  denotes chlorine, bromine, iodine, —O—COCH 3 , tosylate or mesylate,  
 is reacted with a compound of formula (III),  
                     
 optionally in a suitable diluent and/or in the presence of a suitable added reagent or catalyst,  
 wherein the reaction is carried out in a temperature range from 20 to 80° C.  
 
     
     
         2 . The process according to  claim 1 , wherein a diluent is used which is selected from the group consisting of acetonitrile, N-methylpyrrolidinone, tetrahydrofuran, acetone, ethanol and dichloromethane.  
     
     
         3 . The process according to  claim 1 , wherein acetonitrile is used as diluent.  
     
     
         4 . The process according to  claim 1 , wherein the reaction is carried out at a temperature of about 60 to 75° C.  
     
     
         5 . The process according to  claim 1 , wherein the compound of formula (II) is used in a molar ratio of 1:1 to 1:3 to the compound of formula (III).  
     
     
         6 . The process according to  claim 1 , wherein the compound of formula (II) is used in a molar ratio of about 1:2 to the compound of formula (III).  
     
     
         7 . The process according to  claim 1 , wherein an added reagent and/or catalyst is used, selected from the group consisting of p-toluenesulphonic acid monohydrate, sodium hydrogen carbonate, sodium acetate, pyridine, dimethylaminopyridine, magnesium sulphate, triethylamine, trimethylorthoformate and tetrabutylammonium bromide.  
     
     
         8 . The compound of formula (II)  
       
         
           
           
               
               
           
         
       
       wherein 
 R 1  denotes bromine.  
 
     
     
         9 . A process for preparing a compound of formula (II)  
       
         
           
           
               
               
           
         
       
       wherein 
 R 1  denotes bromine,  
 wherein,  
 a compound of formula (IV)  
                     
 is reacted with elemental bromine in a diluent.  
 
     
     
         10 . The process according to  claim 9 , wherein the diluent is dichloromethane.  
     
     
         11 . A process for preparing a compound of formula (I)  
       
         
           
           
               
               
           
         
       
       said process comprising the following steps: 
 a) reacting the compound of formula (IV)  
                     
  with elemental bromine in an organic diluent at a temperature of 30 to 50° C.,  
 b) washing the reaction mixture with water,  
 c) after phase separation, concentrating the organic phase by evaporation and optionally diluting it with another organic diluent, and  
 d) reacting the concentrated organic phase with the compound of formula (III)  
                     
 at 20 to 80° C. without isolating the intermediate product of steps a) to c).