Catalytic parallel kinetic resolution under homogeneous conditions.
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.
Duffey
Trisha A
TA
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
Mackay
James A
JA
Vedejs
Edwin
E
D002384:Catalysis; D007700:Kinetics; D008744:Methylamines / Q000737:chemistry*; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
D008744:Methylamines; C548437:N-methyl-1-(pyridin-2-yl)methanamine; D010720:Phosphines; D011725:Pyridines; C044646:phosphine