Enzymatic thiol Michael addition using laccases: Multiple C-S bond formation between p-hydroquinones and aromatic thiols

Laccases create C-C, C-O or C-N bonds and have been investigated intensively as catalysts for green chemistry and white biotechnology. However, little is known about C-S bond formation in laccasecatalyzed reactions. We have used the laccases from Pycnoporus cinnabarinus and Myceliophthora thermophila to create heteromolecular reaction products from p-hydroquinones and aromatic thiols via C-S bond formation. We discovered a broad assortment of different thiolated products, ranging from dimers to tetramers. During laccase-catalysis of the aromatic thiols without p-hydroquinones homomolecular dimers were formed and these were always linked by S-S bonds. The use of laccase is a convenient way to form heteromolecular thiolated products and homomolecular S-n S bonds under eco-friendly environments. (C) 2016 Elsevier B.V. All rights reserved.