Method of synthesizing a functionalized biphenol compound by electrochemical coupling

Abstract

Disclosed herein are methods of synthesizing functionalized biphenol compounds comprising a step wherein a functionalized phenol starting material is subjected to an electrochemical coupling reaction to form a functionalized biphenol compound. The electrochemical coupling reaction can be an oxidative coupling reaction or a reductive coupling reaction. In certain aspects, the methods can be used to synthesize the compounds 4,4′-dihydroxy-[1,1′-biphenyl-3,3′-dialdehyde](dobpda) and 4,4′-dihydroxy-[1,1′-biphenyl-3,3′-dicarboxylic acid](dobpdc).

What is claimed is: 
     
         1 . A method of synthesizing a functionalized biphenol compound comprising the steps of providing a solution comprising a phenol compound functionalized with at least one substituent which is —COOH or a non-halogen substituent that is convertible to a —COOH substituent in a solvent, and subjecting said functionalized phenol compound to an electrochemical coupling reaction whereby two of said functionalized phenol molecules couple together thereby forming a functionalized biphenol compound having a C—C bond between two phenol rings. 
     
     
         2 . The method of  claim 1  wherein said non-halogen substituent that is convertible to a —COOH substituent is —CN or C(═O) R1 where R1 is selected from H, an alkyl, and an —O-alkyl. 
     
     
         3 . The method of  claim 2  wherein said electrochemical coupling reaction is a reductive coupling reaction. 
     
     
         4 . The method of  claim 3  wherein said functionalized phenol compound is further functionalized with a leaving group, which leaving group leaves the functionalized phenol compound to form a coupling site, such that a C—C bond is formed between two coupling sites. 
     
     
         5 . The method of  claim 3  wherein R1 is not —OH, and the symmetrical functionalized biphenol compound that is the product of the electrochemical reductive coupling step is subjected to an oxidation step or a hydrolysis step to convert the non-halogen substituent to —C(═O) OH to produce a biphenol dicarboxylate compound. 
     
     
         6 . The method of  claim 1  wherein said solvent is selected from water, one or more alkyl alcohols, and a mixture of water and one or more alkyl alcohols. 
     
     
         7 . The method of  claim 4  wherein said leaving group is a halogen. 
     
     
         8 . The method of  claim 7  wherein said functionalized phenol is 5-bromosalicylaldehyde. 
     
     
         9 . The method of  claim 1  wherein said electrochemical coupling reaction is an oxidative coupling reaction. 
     
     
         10 . The method of  claim 9  wherein said functionalized phenol compound is salicylic acid. 
     
     
         11 . A method of synthesizing a functionalized biphenol compound comprising the steps of:
 providing a solution comprising a functionalized phenol compound, said functionalized phenol compound comprising a phenol compound functionalized with at least one substituent selected from a —COOH group and a non-halogen substituent that is convertible to a —COOH substituent in a solvent, wherein said non-halogen substituent is selected from —CN group or C(═O) R1, wherein R1 is selected from H, an alkyl, and an —O-alkyl; and   treating said solution electrochemically to couple at least two of said functionalized phenol molecules in said solution to synthesize a functionalized biphenol compound having a C—C bond between two phenol rings.   
     
     
         12 . The method of  claim 11 , wherein said electrochemical coupling reaction is a reductive coupling reaction. 
     
     
         13 . The method of  claim 12 , wherein said functionalized phenol compound is further functionalized with a leaving group, which leaving group leaves the functionalized phenol compound to form a coupling site, such that a C—C bond is formed between two coupling sites. 
     
     
         14 . The method of  claim 12 , wherein R1 is not —OH, and the symmetrical functionalized biphenol compound that is the product of the electrochemical reductive coupling step is subjected to anoxidation step to convert the non-halogen substituent to —C(═O) OH to produce a biphenol dicarboxylate compound. 
     
     
         15 . The method of  claim 11 , wherein said electrochemical coupling reaction is an oxidative coupling reaction. 
     
     
         16 . The method of  claim 9 , wherein said leaving group is selected from a tosylate group and a mesylate group. 
     
     
         17 . A method of synthesizing a functionalized biphenol compound comprising the steps of:
 providing a solution comprising a functionalized phenol compound, said functionalized phenol compound comprising a phenol compound functionalized with at least one substituent selected from a —COOH group and a non-halogen substituent that is convertible to a —COOH substituent by hydrolysis; and   electrochemically treating said solution to couple at least two of said functionalized phenol molecules in said solution to synthesize a functionalized biphenol compound having a C—C bond between two phenol rings.   
     
     
         18 . The method of  claim 17 , wherein said non-halogen substituent that is convertible to a —COOH substituent is —CN or C(═O) R1, wherein R1 is selected from H, an alkyl, and an —O-alkyl. 
     
     
         19 . The method of  claim 17 , wherein said electrochemical coupling reaction is a reductive coupling reaction. 
     
     
         20 . The method of  claim 17 , wherein said electrochemical coupling reaction is an oxidative coupling reaction.