Laccase-catalyzed synthesis of 2,3-ethylenedithio-1,4-quinones

Laccases (benzenediol:oxygen oxidoreductase EC 1.10.3.2) belong to the family of multicopper oxidases. These environmentally friendly enzymes require O-2 as their only co-substrate and produce H2O as their sole by-product. As a result, they have acquired increasing use in biotechnological applications, particularly in the field of organic synthesis. In the current study, laccases have been employed to successfully couple 1,2-ethanedithiol to various substituted hydroquinones to produce novel 2,3-ethylenedithio-1,4-quinones in good yields via an oxidation-addition-oxidation-addition-oxidation mechanism. The reactions proceeded in one-pot under mild conditions (room temperature, pH 5.0). This study further supports the use of laccases as green tools in organic chemistry. Furthermore, it provides evidence that laccase-catalyzed cross-coupling reactions involving small thiols are possible, in spite of research that suggests small thiols are potent inhibitors of laccases. (C) 2015 Elsevier B.V. All rights reserved.