Chiral Surfactant-Type Catalyst for Asymmetric Reduction of Aliphatic Ketones in Water

A novel chiral surfactant-type catalyst is developed. Micelles formed in water by association of the catalysts themselves, and this was confirmed by TEM analyses. Asymmetric transfer hydrogenation of aliphatic ketones catalyzed by the chiral metallomicellar catalyst gave good to excellent conversions and remarkable stereoselectivities (up to 95% ee). Synergistic effects between the metal-catalyzed center and the hydrophobic microenvironment of the core in the metallomicelle led to high enantioselectivities

Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water

A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst <b>2</b>. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity