Asymmetric Bio- and Organocatalytic Cascade Reaction - Laccase and Secondary Amine-Catalyzed α-Arylation of Aldehydes

An asymmetric bio- and organocatalytic cascade one-pot reaction for the α-arylation of aldehydes is presented. 1,4-Dihydroxybenzene and its derivatives are oxidized to quinones by laccase and aerial oxygen. This catalytic process has been efficiently coupled to asymmetric enamine organocatalysis, affording 3-substituted 2,3-dihydrobenzofuran-2,5-diols in moderate to good yield and moderate to excellent enantioselectivity

NMR in operando Monitoring of Mechanochemically Accelerated Sublimations

Solid-solid interactions in co-crystals lead to alternations of the physico-chemical properties of the mixture compared to its single components. Herein, we report a setup that makes use of mechanochemistry to promote these interactions and is coupled with the analytical power of nuclear magnetic resonance (NMR) to in operando monitor the resulting variation. The system is applied to the analysis of optically active species responding to cases of self-disproportionation of enantiomers (SDE) by sublimation. The fundamentals behind the observed phenomenon led to an advanced concept of enantiomers recognition based on selective sublimation

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