Modern Chemistry & Applications

Nanosheet-enhanced asymmetric catalysis

International Conference on Applied Chemistry

October 17-18, 2016 Houston, USA

Jing He

Beijing University of Chemical Technology, China

Posters & Accepted Abstracts: Mod Chem appl

Abstract:

Transition-metal catalyzed asymmetric reaction is an important strategy to produce optically pure compounds. Recently, utilization of steric effects of inorganic hosts to improve enantioselectivity has attracted much attention in heterogeneous asymmetric catalysis. Success examples have been reported for the promotion of chiral induction by the confinement in the rigid pores of microporous and mesoporous hosts or flexible interlayer region of layered solids. This work focuses on how to utilize the steric effect of rigid planar nanosheet of layered host to enhance the enantioselectivity in metal-catalyzed asymmetric synthesis. Alpha-amino acids, a kind of naturally occurring chiral units, have been intercalated into the interlayer galleries of LDHs by ion-exchange or co-precipitation. Nanosheet-attached L-glutamate, L-alanine, and L-serine were then employed as the ligands of vanadium (V), zinc (II) or Rh (III) centers for asymmetric catalysis. In virtue of the steric synergies of rigid inorganic layers, remarkable enhancement of chiral induction has been achieved in vanadium-catalyzed epoxidation and zinccatalyzed aldol addition reactions. The �??huge�?? inorganic layers can make a stable �??rigid�?? environment around the chiral centre, and thus have significant impact on the enantiomeric selectivity by restricting or directing the access trajectory of reactant molecules. In Rh-catalyzed C-H activation, the nanosheets have been revealed to enhance the catalytic activity by affording the desired basicity and improve the regioselectivity by serving as the rigid substitution of alpha-amino acid ligands.

Biography :

Email: hejing@mail.buct.edu.cn