Third-Generation Amino Acid Furanoside-Based Ligands from <scp>d</scp>
-Mannose for the Asymmetric Transfer Hydrogenation of Ketones: Catalysts with an Exceptionally Wide Substrate Scope
A modular ligand library of α‐amino acid hydroxyamides and thioamides was prepared from 10 different N‐tert‐butyloxycarbonyl‐protected α‐amino acids and three different amino alcohols derived from 2,3‐O‐isopropylidene‐α‐d‐mannofuranoside. The ligand library was evaluated in the half‐sandwich ruthenium‐ and rhodium‐catalyzed asymmetric transfer hydrogenation of a wide array of ketone substrates, including
Mild and Practical Reductions of Prochiral Ketones to Chiral Alcohols Using the Chiral Boronic Ester TarB-H
作者:Bakthan Singaram、Scott Eagon、Jinsoo Kim
DOI:10.1055/s-0028-1083605
日期:2008.12
Chiral alcohols are prepared under mild conditions in high enantiomeric excesses using the tartaric acid derived chiral boronic ester TarB-H. The phenylboronic acid was quantitatively recovered and recycled using a simple extraction with sodium hydroxide and diethyl ether. Aromatic and aliphatic secondary alcohols were prepared in up to 99% ee.
Synthesis of Chiral Aromatic Alcohols: Use of New C<sub>2</sub>-Symmetric Rh<sup>III</sup>Cp∗, Ru<sup>II</sup>(cymene), or Ru<sup>II</sup>(benzene) Complexes Containing Chiral Diaminocyclohexane Ligand as Asymmetric Transfer Hydrogenation Catalyst
Abstract Twelve chiral secondary alcohols were synthesized by asymmetrictransferhydrogenation (ATH) using C2-symmetric bis(sulfonamide) ligand (2) derived from (1R,2R)-cyclohexane-1,2-diamine and complexed with [RhCl2Cp*]2, [RuCl2(cymene)]2, or [RuCl2(benzene)]2 and then used in situ in the reduction of prochiral ketones. The alcohols were obtained in 85–99% yield and 90–99% enantioselectivity with