Hydrogenation Of Simple Ketones Research Articles

Iridium-Catalyzed Asymmetric Hydrogenation of Simple Ketones

Iridium-Catalyzed Asymmetric Hydrogenation of Simple Ketones

Phosphine-free chiral iridium catalysts for asymmetric catalytic hydrogenation of simple ketones

Phosphine free iridium catalysts with simple structures show efficient enantioselectivities and activities in the asymmetric hydrogenation of simple ketones by using chiral iridium catalysts to chiral alcohols with up to 96% ee.

ChemInform Abstract: Rapid, Productive and Stereoselective Hydrogenation of Ketones

RuCl2(phosphine)2(1,2-diamine) complexes act as excellent precatalysts for homo- geneous hydrogenation of simple ketones which lack any functionality capable of interacting with the metallic center. This newly devised catalytic system allows preferential saturation of a CaO function over a coexisting CaC linkage in 2-propanol containing an alkaline base. Furthermore, the stereoselectivity of the reaction is easily controlled by the electronic and steric properties (bulkiness and chirality) of the ligands as well as the reaction conditions. Selective reduction of carbonyl compounds to alcohols has relied heavily on the use of metal hydride reagents. Our goal is to replace such stoichiometric reductions by catalytic hydrogenation, because the latter is obviously more beneficial, particularly for large-scale reactions. Here we describe a very practical homogeneous hydrogenation of ketones catalyzed by RuCl2(phosphine)2(1,2-diamine) and an inorganic base. The precatalysts can be preformed or generated in situ by mixing the phosphine-RuCl2 complex and an appropriate 1,2-diamine in 2-propanol. The reaction is normally conducted at room temperature and at < 8 atm of hydrogen. The new method shows promise for the synthesis of a wide range of achiral and chiral alcohols from ketonic substrates. This chemistry is entirely different from the BINAP-Ru catalyzed asymmetric hydrogenation of functionalized ketones developed earlier in our laboratories (1). RAPID HYDROGENATION OF SIMPLE KETONES

ChemInform Abstract: Developing a Chiral Toolbox for Asymmetric Catalytic Reactions

During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. The research in our group addresses fundamental and practical problems in this field by developing a diverse set of chiral ligands that combine with transition metals to form highly enantioselective catalysts. Families of tridentate ligands have been developed for the enantioselective hydrogenation of unfunctionalized substrates. In addition, we have developed several new bidentate phosphine ligands for asymmetric catalysis. The common feature of these ligands are that they contain rigid aromatic backbones or ring structures which restrict conformational flexibility of the ligands. Several asymmetric reactions have been studied: asymmetric hydrogenation of functionalized substrates such as N-acylaminoacrylic acids, enamides and enol acetates; asymmetric hydrogenation of simple ketones, and imines; and asymmetric carbon-carbon bond forming reactions. In addition, we have designed and synthesized several novel chiral monophosphines for asymmetric catalytic reactions. Transition metal complexes with these monophosphines have also been developed for asymmetric transformations.

Highly Efficient Asymmetric Hydrogenation of Alkyl Aryl Ketones Catalyzed by Iridium Complexes with Chiral Planar Ferrocenyl Phosphino‐Thioether Ligands

AbstractIridium complexes of planar‐chiral ferrocenyl phosphine‐thioether ligands were tested in the hydrogenation of simple ketones. Optimization of the conditions led to a highly active catalytic system with turnover numbers up to 915 and turnover frequencies up to ca. 250 h−1. Furthermore, very high enantioselectivities (up to &gt;99 %) together with complete conversions were obtained for the asymmetric hydrogenation of various acetophenones at 10 °C.