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Catalysts for Hydrogenization

Highly Selective Hydrogenation Catalysts

Three-component catalysts, effective in the hydrogenation of simple ketones, are composed of Ruthenium(II) complexes with phosphine ligands(or diphosphine), 1,2-diamine, and a strong base. These catalysts were discovered by NOYORI Molecular Catalysis Project of Exploratory Research for Advanced Technology (ERAT) organized by Japan Science and Technology Corporation (JST). Subsequently, Exploration and Application Study (participants: Nagoya University, Aichi Institute of Technology, Tokyo Institute of Technology, Sumitomo Chemical Co., Ltd., Takasago International Corporation, Nissan Chemical Ind., Ltd., Nippon Soda Co., Ltd., and Kanto Chemical Co., Inc.), supported by JST, improved the stability and ease of use of the Ruthenium(II) complexes through the development of a two-component catalyst.

These catalysts facilitate a highly efficient hydrogenation of simple ketones. In addition to high activity, the carbonyl-selective hydrogenation of aldehydes and ketones with conjugated or unconjugated carbon-carbon multiple bonds¹⁾ and the diastereoselective hydrogenation of various ketones²⁾³⁾ is performed smoothly under mild conditions, such as at room temperature and/or under low hydrogen pressure(1 to 10 atom) resulting in corresponding alcohols in nearly quantitative yields. Chiral Ruthenium (II)-diphosphine complex, in combination with appropriate chiral diamine, catalyzes enantioselective hydrogenation of prochiral ketones to give chiral alcohols od a very high enantiomeric purity^1)3),4). Furthermore, this catalyst is environmentally conscientious because of minimal metal disposal after the reaction, compared to the stoichiometric reduction with metal hydride reagents and the use of 2-propanol as a solvent⁵⁾.

Example of Hydrogenation

1. Hydrogenation of unsaturated aldehydes and ketones¹⁾ Carbonyl compounds with conjugated or unconjugated carbon-carbon multiple bonds can be converted rapidly and quantitatively to the corresponding unsaturated alcohols.

2. Diastereoselective hydrogenation of ketones²⁾

3. Enantioselective hydrogenation of ketones^1)3),4)

We are now able to offer the ready-to-use Ruthenium(II) complexes composed of this improved Ruthenium(II) complex and a strong base⁶⁾. The end result is an exceedingly efficient hydrogenation of simple ketones, which rates and productivities from one to two orders of magnitude higher than those obtained with three-component catalyst^1)-4), keeping the high selectivity. We recommend this catalyst for laboratory use or an improvement of your production process.

References

1) T. Ohkuma, H. Ooka, T. Ikariya, and R. Noyori, Preferential Hydrogenation of Aldehydes and Ketones, J. Am. Chem. Soc., 117, 10417-10418 (1995)

2) T. Ohkuma, H. Ooka, M. Yamakawa, T. Ikariya, and R. Noyori, Stereoselective Hydrogenation of Simple Ketones Catalyzed by Ruthenium( II ) Complexes, J. Org. Chem., 61, 4872-4873 (1996)

3) T. Ohkuma, H. Ooka, S. Hashiguchi, T. Ikariya, and R. Noyori, Practical Enantioselective Hydrogenation of Aromatic Ketones, J. Am. Chem. Soc., 117, 2675-2676 (1995)

4) T. Ohkuma, H. Ikehira, T. Ikariya, and R. Noyori, Asymmetric Hydrogenation of Cyclica,ß-Unsaturated Ketones to Chiral Allylic Alcohols, Synlett, 467-468 (1997)

5) T. Ohkuma, R. Noyori, Asymmetric Hydrogenation of Simple Ketone, Journal of Synthetic Organic Chemistry, Japan,57,553-563 (1996)

6) H. Doucet, T. Ohkuma, K. Murata, T. Yokozawa, M. Kozawa, E. Katayama, A. F. England, T. Ikariya, and R. Noyori, trans-[RuCl2(phosphane)2(1,2-diamine)] and Chiral trans-[RuCl2(diphosphane) (1,2-diamine)]: Shelf-Stable Precatalysts for Rapid, Productive, and Stereoselective Hydrogenation of Ketones, Angew. Chem., Int. Ed. Engl., 37, 1703-1707 (1998)

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