Tyrosinases in Organic Chemistry: A Versatile Tool for the -Arylation of -Dicarbonyl Compounds

A tyrosinase-mediated arylation towards a variety of different building blocks is presented. Utilizing phenol or simple substituted phenols, the corresponding quinones are synthesized in a two-step procedure by an enzyme-catalyzed oxidation (tyrosinase from Aspergillus oryzae). The activated intermediates undergo a 1,4-addition with selected -dicarbonyl compounds. Starting from phenol, yields of isolated product for the hydroxylation-oxidation-arylation sequence range from 43-77%, whereas substituted acceptors provided 9-55%, only. Different substitution patterns on phenol revealed that electron donating functionalities are preferentially accepted to electron withdrawing ones, whereas ortho-substituted phenols are not accepted at all.