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Operationally Simple enantioselective Silane reduction of Ketones by the [Ir(OMe)(cod)]₂/Azolium Catalytic System

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International Journal of Organic Chemistry 2024年第1期14卷 1-19页

作者： Satoshi Sakaguchi Chika Nagao Ryo Ichihara Shogo Matsuo Department of Chemistry and Materials Engineering Faculty of Chemistry Materials and Bioengineering Kansai University Suita Japan

An operationally simple protocol was designed for the enantioselective silane reduction (ESR) of ketones using air- and moisture-stable [Ir(OMe)(cod)]2 (cod = 1,5-cyclooctadiene) (3) as a metal catalyst precursor. This reaction was driven by chiral hydroxyamide-functionalized azolium salt 2. The catalytic ESR reaction could be performed under benchtop conditions at room temperature. Treatment of 2 with 3 in THF yielded the monodentate IrCl(NHC)(cod) (NHC = N-heterocyclic carbene) complex 4 in 93% yield, herein the anionic methoxy ligand of 3 serves as an internal base that deprotonates the azolium ring of 2. The well-defined Ir complex 4 catalyzed the ESR reaction of propiophenone (6) with (EtO)2MeSiH using the pre-mixing reaction procedure. Based on this success, the catalytic ESR reaction was designed and implemented using an in situ-generated NHC/Ir catalyst derived from 2 and 3. Thus, a wide variety of aryl ketones could be reduced to the corresponding optically active alcohols in moderate to excellent stereoselectivities at room temperature without temperature control. Since the high catalytic activity of 3 was observed, we next evaluated several other transition metal catalyst precursors for the catalytic ESR reaction under the influence of 2. This evaluation revealed that Ir(acac)(cod) (acac = acetylacetonate) (28) and [IrCl(cod)]2 (5) can be successfully used as metal catalyst precursors in the ESR reaction.

关键词： Asymmetric Catalysis enantioselective reduction Hydrosilylation Reaction N-Heterocyclic Carbene Iridium

Studies on the Oxazaborolidine-catalyzed enantioselective reduction of 3-Morpholin-4-yl-1-phenyl-1-propanone with Density Functional Theory

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Chinese Journal of Structural Chemistry 2005年第4期24卷 413-418页

作者： FANJian-Fen LUYun-Xiang WANGQiu-Xia WULi-Fen SUNYun-Peng DepartmentofChemistry SuzhouUniversitySuzhou215006China

Density functional theory (DFT) has been applied to study the enantioselective reduction of 3-morpholin-4-yl-1-phenyl-1-propanone with borane catalyzed by (S)-4-benzyl-5,5- diphenyl-1,3,2-oxazaborolidine at the B3LYP/6-31G* level. All molecular species involved in the four reaction steps have been fully optimized and the structural parameters are provided, and the micro process of reaction was also investigated. The catalyst-alkoxyborane adduct formed in step III exhibits a B-O-B-N tetra-atomic ring. Reaction coordination calculations show that BH3 can react with 3-morpholin-4-yl-1-phenyl-1-propanone spontaneously, resulting in the need of 2 mol BH3 in the reaction.

关键词： B3LYP/6-31G* 3-morpholin-4-yl-1-phenyl-1-propanone enantioselective reduction

Quantum chemical study on the mechanism of enantioselective reduction of prochiral ketones catalyzed by oxazaborolidines

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Science China Chemistry 2001年第6期44卷 616-626页

作者：李明谢如刚田安民 Department of Chemistry Southwest-China Normal University Chongqing China Department of Chemistry Sichuan University Chengdu China

Theab initio molecular orbital study on the mechanism of enantioselective reduction of 3,3-dimethyl butanone-2 with borane catalyzed by chiral oxazaborolidine is performed. As illustrated, this enantioselective reduction is exothermic and goes mainly through the formations of the catalyst-borane adduct, the catalyst-borane-3,3-dimethyl butanone-2 adduct, and the catalyst-alkoxyborane adduct with a B-O-B-N 4-member ring and through the decomposition of the catalyst-alkoxyborane adduct with the regeneration of the catalyst. During the hydride transfer in the catalyst-borane-3,3-dimethyl butanone-2 adduct to form the catalyst-alkoxyborane adduct, the hydride transfer and the formation of the B-O-B-N 4-member ring in the catalyst-alkoxyborane adduct happen simultaneously. The controlling step for the reduction is the transfer of hydride from the borane moiety to the carbonyl carbon of 3,3-dimethyl butanone-2. The transition state for the hydride transfer is a twisted chair structure and the reduction leads to R-chiral alcohols.

关键词： chiral oxazaborolidine 3,3-dimethyl butanone-2 enantioselective reduction ab initio.

Catalytic enantioselective reduction of Prochiral Ketones with Chiral Ferrocenyl Amino Alcohols

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Chinese Journal of Chemistry 2004年第3期22卷 306-309页

作者：陈维一陆军沈宗旋张雅文 Department of Chemistry and Chemical Engineering Suzhou University Suzhou Jiangsu 215006 China

The asymmetric reduction of prochiral ketones was catalyzed by a class of recoverable and highly stable chiral ferrocenyl amino alcohols derived from natural amino acids to yield optically active secondary alcohols in... 详细信息

关键词： enantioselective reduction prochiral ketone NaBH4/I2 combination ferrocenyl amino alcohol

Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

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有机化学 2003年第Z1期23卷 25-26页

作者： CHEN Xiao ZHANG Yong-Xin DU Da-Ming HUA Wen-Ting Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University Beijing 100871

The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.……

关键词： enantioselective reduction molecular recognition catalytic reaction prochiral ketones organic compounds chiral ligand