Stereospecific method for the preparation of dioxa-bicyclooctane nitrate compounds

Abstract

This invention relates to a new method for the stereospecific thiocarboxylation and nitration of organic compounds for the preparation of compounds according to formula (I): comprising the following steps: (a) reacting a compound of formula (II): with a sulfonic derivative of formula (III) wherein the R is selected from the groups C 1-3 -alkyl, C 1-3 -alkyl substituted with 1 to 3 halogen atoms, phenyl, C 1-3 -alkyl-phenyl and C 1-3 -alkyl-phenyl wherein the alkyl is substituted with 1 to 3 halogen atoms and G is a halogen atom or a group —O—SO 2 —R wherein R is as hereinabove defined to yield a compound of formula (IV) (b) treating compound (IV) with a thiocarboxylic acid of formula (V) or a salt thereof: wherein Z is as defined above, to yield compound (VI) and (c) treating compound (VI) with tetrabutylammonium nitrate to yield a compound of formula (I).

1 . A method for the preparation of a compound of formula (I): 
       
         
           
           
               
               
           
         
         wherein Z represents a C 1-6 -alkyl, C 2-6 -alkenyl, C 3-8 -cycloalkyl, aryl, heteroaryl, aryl C 1-6 -alkyl, or heteroaryl-C 1-6 -alkyl group, optionally substituted by one to three groups independently selected from the group consisting of halogen, C 1-6 -alkyl and C 1-6 -alkylthio, 
         comprising the following steps: 
         (a) reacting a compound of formula (II): 
       
       
         
           
           
               
               
           
         
         with a sulfonic derivative of formula (III) 
       
       
         
           
           
               
               
           
         
         wherein the R is selected from the groups C 1-3 -alkyl, C 1-3 -alkyl substituted with 1 to 3 halogen atoms, phenyl, and C 1-3 -alkyl-phenyl wherein the alkyl is substituted with 1 to 3 halogen atoms and G is a halogen atom or a group —O—SO 2 —R wherein R is as hereinabove defined 
         to yield a compound of formula (IV) 
       
       
         
           
           
               
               
           
         
         wherein R has the meaning defined for formula (III) 
         (b) treating compound (IV) with a thiocarboxylic acid of formula (V) or a salt thereof: 
       
       
         
           
           
               
               
           
         
         wherein Z is as defined for formula (I), to yield compound (VI) 
       
       
         
           
           
               
               
           
         
         wherein Z is as defined for formula (I) and R is as defined for formula (III) 
         and 
         (c) treating compound (VI) with tetrabutylammonium nitrate to yield a compound of formula (I). 
       
     
     
         2 . The method according to  claim 1 , wherein in the compound of formula (I), the thiocarboxylate Z—C(═O)—S— group is trans to the nitrate group. 
     
     
         3 . The method according to  claim 1 , wherein Z represents a C 1-6 -alkyl, C 2-6 -alkenyl, aryl, or heteroaryl group. 
     
     
         4 . The method according to  claim 3 , wherein Z is selected from the group consisting of methyl, ethyl, n-propyl, or n-butyl. 
     
     
         5 . The method according to  claim 4 , wherein Z represents a methyl group. 
     
     
         6 . The method according to  claim 1  wherein a sodium, potassium, cesium, magnesium or calcium salt of the thiocarboxylic acid of formula (V) is used. 
     
     
         7 . The method according to  claim 6  wherein a potassium salt of the thiocarboxylic acid of formula (V) is used. 
     
     
         8 . The method according to  claim 1  wherein the sulfonic derivative of formula (III) is selected from a sulfonyl chloride or a sulfonyl anhydride. 
     
     
         9 . The method according to  claim 8  wherein the sulfonic derivative of formula (III) is selected from the group comprising trifluoro-methanesulfonic anhydride, 4-methylbenzesulfonic anhydride or methylsulfonic anhydride. 
     
     
         10 . The method according to  claim 9  wherein the sulfonic anhydride is trifluoro-methanesulfonic anhydride. 
     
     
         11 . The method according to  claim 1  wherein step b) is carried out by dissolving compound (IV) in an aprotic solvent and reacting this solution with an aqueous solution comprising a thiocarboxylic acid of formula (V) or a salt thereof in the presence of a phase transfer catalyst. 
     
     
         12 . The process according to  claim 1  wherein step c) is carried out using the reaction mixture from claim b) without isolating the compound of formula (VI). 
     
     
         13 . The method according to  claim 1  wherein step c) is carried out using tetrabutylammonium nitrate as a nitrating agent. 
     
     
         14 . The method according to  claim 13  wherein step b) is carried out by adding tetrabutylammonium nitrate to a solution of compound (IV) in an aprotic solvent. 
     
     
         15 . The method according to  claim 14  wherein the reaction of step c) is carried out by heating the mixture at a temperature from 60 to 90° C. during a period of 2 to 8 hours. 
     
     
         16 . The method according to  claim 1  wherein step c) is carried out using the reaction mixture from claim b) without isolating the compound of formula (VI). 
     
     
         17 . A compound of formula (VI) 
       
         
           
           
               
               
           
         
         wherein the R is selected from the groups C 1-3 -alkyl, C 1-3 -alkyl substituted with 1 to 3 halogen atoms, phenyl, and C 1-3 -alkyl-phenyl wherein the alkyl is substituted with 1 to 3 halogen atoms and Z represents a C 1-6 -alkyl, C 2-6 -alkenyl, C 3-8 -cycloalkyl, aryl, heteroaryl, aryl C 1-6 -alkyl, or heteroaryl-C 1-6 -alkyl group, optionally substituted by one to three groups independently selected from the group consisting of halogen, C 1-6 -alkyl and C 1-6 -alkylthio. 
       
     
     
         18 . A compound of formula (IV) 
       
         
           
           
               
               
           
         
         wherein R represents a trifluoromethyl group.