Dendritic Organosilica Nanoparticle‐Based Metal‐Enzyme Hybrid Catalyst for Chemoenzymatic Deracemization of Cyclic Amines

Abstract

The synthesis of enantiopure chiral cyclic amines is of critical importance but highly challenging. In this study, a metal‐enzyme hybrid catalyst was fabricated by the co‐immobilization of palladium nanoparticles and monoamine oxidases on dendritic organosilica nanoparticles (DONs) for chemoenzymatic deracemization, furnishing a panel of chiral cyclic amines in high enantioselectivities (96–98 % ee). Catalyst optimization revealed that the ultra‐high specific surface area, mesoporous channels and hydrophobic microenvironment of the DONs are responsible for the improved catalyst stability, activity and catalytic efficiency.

Strategies for chiral separation: from racemate to enantiomer

“…Theoretically, it can be coupled with various enantioseparation methods such as PsC, 82 ELLE, 53 and kinetic resolution (KR). 83 However, crystallization possesses the highest compatibility with deracemization (Section 5). This is because the size-dependent solubility difference between two enantiomers can be naturally and easily induced by simple physical processes during crystallization, such as boiling, 84 agitation, 85 temperature cycling, 86 homogenization 87 and grinding, 88 thereby leading to a concentration difference between enantiomers for initializing racemization.…”