Heterogeneous Enantioselective Catalytic Reduction of Ketones

Enantioselective Synthesis of Alcohols and Amines by Iridium‐Catalyzed Hydrogenation, Transfer Hydrogenation, and Related Processes

“…after three days) and recycling was unsuccessful. [118] The same group used the diurea ligand (S,S)-100 with [MClA C H T U N G T R E N N U N G (cod)] 2 (M = Rh, Ir). Although, ee values up to 80 % were obtained with rhodium, and even higher (95 % ee) in the case of a heterogeneous polyurea-rhodium catalyst, the maximum ee obtained with iridium in the reduction of acetophenone was 57 % (Scheme 52).…”

Immobilization of a Modified Tethered Rhodium(III)‐p‐Toluenesulfonyl‐1,2‐diphenylethylenediamine Catalyst on Soluble and Solid Polymeric Supports and Successful Application to Asymmetric Transfer Hydrogenation of Ketones

“…For instance, Lemaire and co-workers prepared copolymers made of styrene-p-sulfonyl-DPEN and styrene/divinylbenzene which were used with different metal precursors. [23] Although first recycling results were poor, this approach was successfully followed by other groups. [24][25][26] Solid organic and inorganic supports, to which TsDPEN or derivatives were covalently bound, have also widely been used, [27][28][29][30][31][32] and some attempts have been made to use soluble supported [33,34] as well as micellar-embedded TsDPEN-based catalysts.…”

Preparation of Chiral Ligands Connected with Quaternary Ammonium Group for Recyclable Catalytic Asymmetric Transfer Hydrogenation in Ionic Liquid

“…Indeed, transfer hydrogenation using polymer-or dendritic-supported TsDPEN ligand under heterogeneous conditions has been reported. [6][7][8][9][10][11][12][13] Serving as a new type of solvent for green technology are ionic liquids (ILs), which consist of ions such as quaternary ammonium or phosphonium ions and are liquids at room temperature.14-18) Although the toxicity and biodegradability of ILs have not been sufficiently explored, they are known to be non-volatile and non-flammable.14-19) Therefore, the use of ILs offers safety and environmental protection, as well as eliminates the problem of volatilization loss, which occurs with conventional organic solvents. In addition, ILs have the ability to dissolve organic and inorganic compounds, while being immiscible with less polar solvent and water.…”

“…Indeed, transfer hydrogenation using polymer-or dendritic-supported TsDPEN ligand under heterogeneous conditions has been reported. [6][7][8][9][10][11][12][13] Serving as a new type of solvent for green technology are ionic liquids (ILs), which consist of ions such as quaternary ammonium or phosphonium ions and are liquids at room temperature. [14][15][16][17][18] Although the toxicity and biodegradability of ILs have not been sufficiently explored, they are known to be non-volatile and non-flammable.…”

“…13 C-NMR (CD 3 35-1.43 (2H, m, CH 2 ), 1.46-1.54 (2H, m, CH 2 ), 1.70-1 6 ] (1.0 mL) with stirring under N 2 , followed by addition of a formic acid-triethylamine azeotropic mixture 31) (bp 108°C/29 mmHg, 0.5 mL). The reaction mixture was stirred at rt for 24 h. Next, n-hexane (5 mL×3) was added to the reaction mixture and the products were extracted by decantation of the upper layer, and the residual IL phase was dried in vacuo for 30 min.…”