Differentiation of Epoxide Enantiomers in the Confined Spaces of an Homochiral Cu(II) Metal-Organic Framework by Kinetic Resolution.

TAMOF-1, a homochiral metal-organic framework (MOF) constructed from an amino acid derivative and Cu(II), was investigated as a heterogeneous catalyst in kinetic resolutions involving the ring opening of styrene oxide with a set of anilines. The branched products generated from the ring opening of styrene oxide with anilines and the unreacted epoxide were obtained with moderately high enantiomeric excesses. The linear product arising from the attack on the non-benzylic position of styrene oxide underwent a second kinetic resolution by reacting with the epoxide, resulting in an amplification of its final enantiomeric excess and a concomitant formation of an array of isomeric aminodiols. Computational studies confirmed the experimental results, providing a deep understanding of the whole process involving the two successive kinetic resolutions. Furthermore, TAMOF-1 activity was conserved after several catalytic cycles. The ring opening of a meso-epoxide with aniline catalyzed by TAMOF-1 was also studied and moderate enantioselectivities were obtained.