Intermolecular reaction of propargyl ethers with dimethylfuran in the presence of gold(i) complexes

Abstract

The present invention relates to a method of preparing ortho substituted phenols from 2,5-dimethylfuran and propargyl ethers in the presence of a gold(I) complex. It is particularly advantageous to use 2,5-dimethylfuran as this offers an ecological beneficial synthesis of said ortho substituted phenols.

1 . A process of preparing a compound of formula (I) 
       
         
           
           
               
               
           
         
         comprising the step of reacting compound of formula (II) with compound of formula (III) 
       
       
         
           
           
               
               
           
         
         wherein R 1  represents a C 1-10 -alkyl group or a C 4-7 -cycloalkyl group; 
         in the presence of a gold(I) complex. 
       
     
     
         2 . The process according to  claim 1 , wherein R 1  represents a C 1-6 -alkyl group, preferably a C 1-3 -alkyl group, more preferably a methyl group. 
     
     
         3 . The process according to  claim 1 , wherein that the gold(I) complex has the formula [Au(I)OL]AN
 wherein OL represents an organic ligand and AN represents a single charged anion.   
     
     
         4 . The process according to  claim 1 , wherein the gold(I) complex has a single charged anion (AN) which is selected from the group consisting of [BX 4 ] − , [PX 6 ] − , [SbF 6 ] − , [ClO 4 ] − , CF 3 COO − , sulfonates, particularly a sulfonate of formula (AN-II), tetra(3,5-bis(trifluoromethyl)phenyl)borate (BAr F   − ), tetraphenylborate, and anions of formula (AN-I); 
       
         
           
           
               
               
           
         
         wherein 
         X represents a halogen atom; and 
         Y 1  represents a phenyl or a C 1-8 -alkyl group, which preferably is substituted by at least one halogen atom. 
       
     
     
         5 . The process according to  claim 1 , wherein the gold(I) complex has an organic ligand (OL) which is either
 at least one phosphorous containing ligand, particularly a phosphorous containing ligand which is selected from the group consisting of formula (P1), (P2), (P3), (P4), (P5), (P6), (P7) and (P8);   or   at least an imidazole-2-ylidene ligand, particularly 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene (=compound of formula (IM));   or   at least a 1H-1,2,3-triazol ligand, particularly of formula (TR-1) or (TR-2) or (TR-3), more particularly of formula (TR-3);   
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein 
         R 10  and R 11  represent independently from each other either H or a linear or branched C 1-10 -alkyl or C 4-10 -cycloalkyl group; and wherein 
         R 12 , R 13 , R 14  and R 15  represent independently from each other H or a linear or branched C 1-6 -alkyl group; 
         n stands for an integer of 1-6 and n′ stands for 0 or 1 or 2. 
       
     
     
         6 . The process according to  claim 1 , wherein the gold(I) complex is prepared from a gold(I) chloro complex and a silver(I) salt. 
     
     
         7 . The process according to  claim 6  wherein 1 the gold (I) complex is of formula [Au(I)OL]AN
 wherein OL represents an organic ligand and AN represents a single charged anion and the gold (I) complex is prepared by the reaction of Au(I)OLCl and AgAN. 
 
     
     
         8 . The process according to  claim 1 , wherein the gold (I) complex is of formula [Au(I)OL]AN wherein OL represents an organic ligand and AN represents a single charged anion and the gold (I) complex is prepared by the reaction of Au(I)OLCl and NaAN. 
     
     
         9 . The process according to  claim 1 , wherein it comprises a subsequent step a):
 a) separating the compound of formula (I) from compound of formula (IVa) and/or formula (IVb)   
       
         
           
           
               
               
           
         
         wherein the wavy line represents a carbon-carbon bond which is linked to the adjacent carbon-carbon double bond so as to have said carbon-carbon double bond either in the Z or in the E-configuration. 
       
     
     
         10 . The process according to  claim 9 , wherein compound of formula (I) from compound of formula (IVa) and/or (IVb) are separated by chromatography, particularly by chromatography using silica gel as stationary phase. 
     
     
         11 . Compound of formula (I) 
       
         
           
           
               
               
           
         
         wherein R 1  represents a C 1-10 -alkyl group or a C 4-7 -cycloalkyl group. 
       
     
     
         12 . Composition comprising the compound of formula (I) and at least the compound of formula (IVa) or (IVb) 
       
         
           
           
               
               
           
         
         wherein R 1  represents a C 1-10 -alkyl group or a C 4-7 -cycloalkyl group and the wavy line represents a carbon-carbon bond which is linked to the adjacent carbon-carbon double bond so as to have said carbon-carbon double bond either in the Z or in the E-configuration. 
       
     
     
         13 . Composition according to  claim 12 , wherein the total amount of compound of formula (IVa) and (IVb) is at most 80% by weight, preferably at most 70% by weight, more preferably at most 50% by weight, even more preferably at most 20% by weight, most preferably at most 10% by weight, relative to the weight of compound of formula (I). 
     
     
         14 . A process of reducing a compound of formula (I) 
       
         
           
           
               
               
           
         
         by a reducing agent in the presence of a heterogeneous metal catalyst to yield a compound of formula (A) 
       
       
         
           
           
               
               
           
         
         wherein the metal is selected from the group consisting of Ni, Fe, Ir, Pd, Pt, Rh and Ru; wherein R 1  represents a C 1-10 -alkyl group or a C 4-7 -cycloalkyl group. 
       
     
     
         15 . A process for the manufacture of the compound of formula (C) from compound of formula (I) comprising the following steps
 a′) reducing the compound of formula (I) by the process according to  claim 14  to yield a compound of formula (A);   
       
         
           
           
               
               
           
         
         b′) oxidizing the compound of formula (A) to yield a compound of formula (B) by an oxidizing agent 
       
       
         
           
           
               
               
           
         
         c′) reducing the compound of formula (B) to yield a compound of formula (C) by a reducing agent 
       
       
         
           
           
               
               
           
         
       
     
     
         16 . A process for the manufacture of compound of formula (D) from compound of formula (I) comprising the steps
 a′) hydrogenate compound of formula (I) by the process according to  claim 14  to yield compound of formula (A);   
       
         
           
           
               
               
           
         
         b′) oxidizing the compound of formula (A) to yield a compound of formula (B) by an oxidizing agent 
       
       
         
           
           
               
               
           
         
         c′) reducing the compound of formula (B) to yield a compound of formula (C) by a reducing agent 
       
       
         
           
           
               
               
           
         
         d′) condensing isophytol with the compound of formula (C) to yield a compound of formula (D); 
       
       
         
           
           
               
               
           
         
       
     
     
         17 . A process according to  claim 14 , wherein the compound of formula (I) is prepared by a method.