Dynamic Kinetic Resolution of Benzoins by Lipase-Metal Combo Catalysis

摘要

The synthesis of some noncommercial racemic 1,2-diaryl-2-hydroxyethanones (benzoins) is described,optimizing the previously reported methodologies.In a further step,the kinetic resolution of these substrates is reported,obtaining conversions of around 50% and ee_p higher than 99% in very short reaction times.As enzymatic catalyst,after screening of several enzymes,the lipase TL (from Pseudomonas stutzeri) was the most efficient,working in an organic solvent with a very low log P value,such as THF.Finally,the dynamic-kinetic resolution of different benzoins using a lipase-ruthenium-catalyzed transesterification in organic solvents is described for the first time,obtaining conversions up to 90% maintaining the excellent enantioselectivity in all cases.