Method of producing oxocylohexyl or oxocyclohexylene derivatives

Abstract

The invention relates to a method for producing compounds of general formula (I), wherein R t represents an oxocyclohexyl radical which is optionally substituted by a hydroxyl radical, an alkoxy radical, and/or alkyl radicals, or an oxocyclohexenyl radical which is optionally substituted by a hydroxyl radical, an alkoxy radical, and/or alkyl radicals, the oxo groups being in the form of an acetal, a ketone, or an enol ether, and R 2 represents a hydroxy group or a protective group which can be transformed into a hydroxy group by means of hydrolysis. A compound of general formula (II) is cathodically reduced in a divided or partially divided electrolysis cell at a pH value of between 2 and 9.

1 - 11 . (Canceled)  
     
     
         12 . A process for the preparation of compounds of the formula I or I′ 
       
         
           
           
               
               
           
         
       
       in which R 1  is an oxocyclohexyl radical optionally substituted by a hydroxyl radical, an alkoxy radical and/or alkyl radicals or an oxocyclohexenyl radical optionally substituted by a hydroxyl radical, an alkoxy radical and/or alkyl radicals, where the oxo groups can be present in the form of an acetal, ketone or enol ether and where in the case in which the oxygen atoms of the hydroxyl group and the enol ether group are bonded to vicinal C atoms, these two oxygen atoms are optionally connected by a C 1 - to C 4 -alkylene unit which is optionally substituted by alkyl radicals, or is a radical of the formula IIIa or IIIc,  
       
         
           
           
               
               
           
         
         in which R 3 , R 4  and R 5  independently of one another are hydrogen or optionally substituted C 1 -C 4 -alkyl and R 5  is substituted C 1 -C 4 -alkyl, or the radicals R 3  and R 4  form a cycloheptyl or cyclohexyl ring together with the carbon atom to which they are bonded and  
         R 2  is a hydroxyl group or a protective group convertible by hydrolysis into a hydroxyl group,  
         in which a compound of the formula II  
         
           
             
             
                 
                 
             
           
         
         in which R 1  and R 2  in each case have the same meaning as in the formula I,  
         is reduced cathodically in a divided or quasi-divided electrolysis cell at a pH of from 2 to 9.  
       
     
     
         13 . A process as claimed in  claim 12 , where the radical R 1  is an oxocyclohexenyl radical optionally substituted by a hydroxyl radical, an alkoxy radical and/or methyl radicals, in which the C—C double bond is in the alpha-position to the oxo group.  
     
     
         14 . A process as claimed in  claim 12 , where the radical R 1  is a radical of the formula IIIa, IIIb or IIId  
       
         
           
           
               
               
           
         
         and R 5  independently of one another is hydrogen or C 1 -C 4 -alkyl.  
       
     
     
         15 . A process as claimed in  claim 12 , where the reduction is carried out in solution using a mixture of water and an inert organic solvent.  
     
     
         16 . A process as claimed in  claim 12 , where, as cathode material, lead, graphite, zinc, copper, silver, tin, stainless steel or mixtures of lead and graphite are used.  
     
     
         17 . A process as claimed in  claim 12 , where the reduction is carried out in a divided cell in which the anode and cathode space are separated from one another by an ion exchange membrane.  
     
     
         18 . A process as claimed in  claim 12 , where the cathodic reduction is performed in a quasi-divided electrolysis cell in which the size of the surface area of the anode (counterelectrode) is 1 to 50% of the surface area of the cathode (working electrode).  
     
     
         19 . A process as claimed in  claim 18 , where the cathodic reduction is performed in a quasi-divided electrolysis cell consisting of a monopolar cathode, a monopolar anode and one or more intermediate bipolar electrodes, where 
 the cathode and the parts of the bipolar electrodes charged in the same sense to this together form the working electrode and the anode and the parts of the bipolar electrodes charged in the same sense to this together form the counterelectrode    the space between counter- and working electrode is undivided    the surface of the counterelectrode consists of electrochemically active and inactive parts    the sum of the electrochemically active parts of the surface of the counterelectrode is smaller by a multiple than that of the electrochemically active parts of the surface of the working electrode.    
     
     
         20 . A process as claimed in  claim 18 , where the electrolysis cell is designed as a stacked plate cell or capillary cell.  
     
     
         21 . A process as claimed in  claim 18 , where the material from which the counterelectrode is prepared is selected from the following group: massive graphite, graphite board, massive metal, massive graphite covered on the electrolyte contact area with a thin layer of metal foil, massive graphite covered on the electrolyte contact area with a cation- or anion-exchange membrane which is optionally coated with a catalyst.  
     
     
         22 . A process as claimed in  claim 18 , where the material from which the working electrode is produced is selected from the following group: massive graphite, graphite felt sheets, carbon felt sheets, fabric having a carbon-covered electrolyte contact area, porous solid, filled with carbon, porous metal.