Enhanced Biocatalytic Performance of Bacterial Laccase from Streptomyces sviceus: Application in the Michael Addition Sequence Towards 3-Arylated 4-Oxochromanes

A fast and efficient laccase-catalysed oxidation/Michael addition sequence is performed using the bacterial laccase Ssl 1 from Streptomyces sviceus under basic conditions to provide a new class of 3-arylated 4-oxochromanes. This approach has advantages compared to previous biocatalytic arylation protocols that use fungal laccases under slightly acidic conditions to allow a significant decrease in reaction time with improved yields and maintained regio- and diastereoselectivity. Furthermore, a successful diastereoselective, consecutive one-pot approach with the use of a hydrogenation flow system combined with the laccase-catalysed arylation was performed. Finally, the general utility of this enzyme as a superior biocatalyst for Michael additions using several nucleophiles was demonstrated. The corresponding starting material was obtained in a straightforward esterification/hydrogenation process with the latter accomplished by using the flow system.