Takao Saito

Oxo-Tethered Ruthenium(II) Complex as a Bifunctional Catalyst for Asymmetric Transfer Hydrogenation and H2 Hydrogenation

Newly developed oxo-tethered Ru amido complexes (R,R)-1 and their HCl adducts (R,R)-2 exhibited excellent catalytic performance for both asymmetric transfer hydrogenation and the hydrogenation of ketonic substrates under neutral conditions without any cocatalysts to give chiral secondary alcohols with high levels of enantioselectivity.

Chiral Ruthenabicyclic Complexes: Precatalysts for Rapid, Enantioselective, and Wide-Scope Hydrogenation of Ketones

A novel ruthenabicyclic complex with base shows excellent catalytic activity in the asymmetric hydrogenation of ketones. The turnover frequency of the hydrogenation of acetophenone reaches about 35,000 min(-1) in the best case, affording 1-phenylethanol in >99% ee. Several aliphatic and base-labile ketones are smoothly converted to the corresponding alcohols in high enantioselectivity. The catalytic cycle for this hydrogenation, in which the ruthenabicyclic structure of the catalyst is maintained, is proposed on the basis of the deuteration experiment and spectroscopic analysis data.

Synthesis of new UV-B light absorbents: (Acetylphenyl)glycosides with antioxidant activities.

m-Acetylphenyl-beta-d-glucopyranosides and m-acetylphenyl-alpha/beta-d-mannopyranosides were synthesized by the Koenigs-Knorr, Mitsunobu, and Helferich reactions as key glycosylation reactions, respectively. Their spectroscopic properties and antioxidative activities were characterized as potential ultraviolet B-ray absorbents.