text: More recently many research groups have tried to employ enzymes into DKR synthetic routes.  Due to the generally high specificity for substrates, enzymes prove to be vital catalysts for binding to only one stereoisomer in the racemic mixture.  In 2007 Bäckvall discovered an enzyme-metal coupled reaction that converts allylic acetates to allylic alcohols with excellent stereospecificity.
  In this reaction, a Pd(0) complex is used to interconvert the chirality of the acetate center at a rate fast enough to ensure complete racemization. When this is achieved the CALB enzyme selectively hydrolyzes the (R) substrate because of the low binding affinity for the (S) substrate. This gives almost exclusively the (R) allylic alcohol in 98% ee.
  To expand on this chemistry, Bäckvall designed a one-pot, two-reaction system that utilizes the stereochemical outcome of a DKR reaction to undergo a second energetically favorable reaction with high enantioselectivity.
  This time a ruthenium complex is used to racemize the allylic alcohol in much the same way as the previous example.  The addition of CALB catalyzes the reaction between the (R) isomer and the ester reagent to form a product with a diene and a dienophile.  This intermediate can then undergo a tandem Diels-Alder reaction to achieve a decent yield with 97% ee.