Catalytic parallel kinetic resolution under homogeneous conditions

Trisha A. Duffey, University of Michigan, Ann Arbor
James A. MacKay, University of Michigan, Ann Arbor
Edwin Vedejs, University of Michigan, Ann Arbor


(Figure Presented) Two complementary chiral catalysts, the phosphine 8d and the DMAP-derived ent-23b, are used simultaneously to selectively activate a mixture of two different achiral anhydrides as acyl donors under homogeneous conditions. The resulting activated intermediates 25 and 26 react with the racemic benzylic alcohol 5 to form enantioenriched esters (R)-24 and (S)-17 by fully catalytic parallel kinetic resolution (PKR). The aroyl ester (R)-24 is obtained with near-ideal enantioselectivity for the PKR process, but (S)-17 is contaminated by ca. 8% of the minor enantiomer (R)-17 resulting from a second pathway via formation of mixed anhydride 27 and its activation by 8d. © 2010 American Chemical Society.