- A well-defined monomeric aluminum complex as an efficient and general catalyst in the Meerwein-Ponndorf-Verley reduction
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The metal-catalyzed Meerwein-Ponndorf-Verley (MPV) reduction allows for the mild and sustainable reduction of aldehydes and ketones but has not found widespread application in organic synthesis due to the high catalyst loading often required to obtain satisfactory yields of the reduced product. We report here on the synthesis and structure of a sterically extremely overloaded siloxide-supported aluminum isopropoxide capable of catalytically reducing a wide range of aldehydes and ketones (52 examples) in excellent yields under mild conditions and with low catalyst loadings. The unseen activity of the developed catalyst system in MPV reductions is due to its unique monomeric nature and the neutral donor isopropanol weakly coordinating to the aluminum center. The present work implies that monomeric aluminum alkoxide catalysts may be attractive alternatives to transition-metalbased systems for the selective reduction of aldehydes and ketones to primary and secondary alcohols.
- McNerney, Brian,Whittlesey, Bruce,Cordes, David B.,Krempner, Clemens
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- “Inverse” Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones
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For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3P=NtBu with the Lewis acid 9-(4-CF3-C6H4)-BBN generated an “inverse” FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with “inverse” FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6F5)3.
- Mummadi, Suresh,Brar, Amandeep,Wang, Guoqiang,Kenefake, Dustin,Diaz, Rony,Unruh, Daniel K.,Li, Shuhua,Krempner, Clemens
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supporting information
p. 16526 - 16531
(2018/10/20)
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- Mild sp2Carbon-Oxygen Bond Activation by an Isolable Ruthenium(II) Bis(dinitrogen) Complex: Experiment and Theory
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The isolable ruthenium(II) bis(dinitrogen) complex [Ru(H)2(N2)2(PCy3)2] (1) reacts with aryl ethers (Ar-OR, R = Me and Ar) containing a ketone directing group to effect sp2C-O bond activation at temperatures below 40 °C. DFT studies support a low-energy Ru(II)/Ru(IV) pathway for C-O bond activation: oxidative addition of the C-O bond to Ru(II) occurs in an asynchronous manner with Ru-C bond formation preceding C-O bond breaking. Alternative pathways based on a Ru(0)/Ru(II) couple are competitive but less accessible due to the high energy of the Ru(0) precursors. Both experimentally and by DFT calculations, sp2C-H bond activation is shown to be more facile than sp2C-O bond activation. The kinetic preference for C-H bond activation over C-O activation is attributed to unfavorable approach of the C-O bond toward the metal in the selectivity determining step of the reaction pathway.
- Lau, Samantha,Ward, Bryan,Zhou, Xueer,White, Andrew J.P.,Casely, Ian J.,MacGregor, Stuart A.,Crimmin, Mark R.
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supporting information
p. 3654 - 3663
(2017/10/03)
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- PRODUCTION METHOD OF OPTICALLY ACTIVE SECONDARY ALCOHOL
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PROBLEM TO BE SOLVED: To provide a chemical catalytic method allowing efficient production of a corresponding optically active secondary alcohol from an aromatic ketone having a substituent at each of two β-positions in an aromatic ring to the carbonyl site, so that both enantiomers can be separately made. SOLUTION: A production method of optically active secondary alcohol is characterized by reacting a ketone compound such as acetophenone derivatives with hydrogen in the presence of a ruthenium complex catalyst having an optically active diphosphine ligand. COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0132; 0140; 0141; 0144; 0151
(2016/11/14)
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- A mild and efficient flow procedure for the transfer hydrogenation of ketones and aldehydes using hydrous zirconia
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A flow chemistry Meerwein-Ponndorf-Verley (MPV) reduction procedure using partially hydrated zirconium oxide via a machine-assisted approach is reported. The heterogeneous reductive system could be applied to a wide range of functionalized substrates, allowing clean and fast delivery of the alcohol products within a few minutes (6-75 min). In three examples the system was scaled to deliver 50 mmol of product.
- Battilocchio, Claudio,Hawkins, Joel M.,Ley, Steven V.
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supporting information
p. 2278 - 2281
(2013/06/05)
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- Kinetic resolution of secondary alcohols using amidine-based catalysts
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Kinetic resolution of racemic alcohols has been traditionally achieved via enzymatic enantioselective esterification and ester hydrolysis. However, there has long been considerable interest in devising nonenzymatic alternative methods for this transformation. Amidine-based catalysts (ABCs), a new class of enantioselective acyl transfer catalysts developed in our group, have demonstrated, inter alia, high efficacy in the kinetic resolution of benzylic, allylic, and propargylic secondary alcohols and 2-substituted cycloalkanols, and thus provide a viable alternative to enzymes.
- Li, Ximin,Jiang, Hui,Uffman, Eric W.,Guo, Lei,Zhang, Yuhua,Yang, Xing,Birman, Vladimir B.
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experimental part
p. 1722 - 1737
(2012/04/04)
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- Catalytic hydrosilylation of carbonyl compounds with zinc(II) acetate: Asymmetric induction collaborated with N2S2 ligands
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Zinc acetate proved to be an efficient catalyst for hydrosilylation of ketones and aldehydes in the combination with (EtO)2MeSiH, and a good to excellent asymmetric induction was observed in the presence of chiral N 2S2 ligands. Georg Thieme Verlag Stuttgart.
- Inagaki, Tomohiko,Yamada, Yoko,Le, Thanh Phong,Furuta, Akihiro,Ito, Jun-Ichi,Nishiyama, Hisao
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experimental part
p. 253 - 256
(2009/05/30)
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- Relationship between the structure and enantioselectivity in the asymmetric reduction of 2′,6′-disubstituted acetophenones with DIP-Chloride. An ab initio study
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Using computational and chemical studies, a relationship between the % ee achieved and the dihedral angles between the plane of the aromatic ring and the plane containing the carbonyl group has been established for asymmetric reductions with B-chlorodiisopinocampheylborane.
- Ramachandran, P. Veeraraghavan,Gong, Baoqing,Brown, Herbert C.,Francisco, Joseph S.
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p. 2603 - 2605
(2007/10/03)
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- A Reinvestigation of the Meerwein-Ponndorf-Verley Reduction: A Highly Efficient Variation Using Zirconium Catalysts
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A new variation of the Meerwein-Ponndorf-Verley reduction based on mechanistic considerations is presented.Under optimized conditions 1-(4-dimethylaminophenyl)ethanol was used as the reducing alcohol (2-4 equiv.), Zr(O-tBu)4 as the catalyst (0.2 equiv.), and toluene or cyclohexane as the solvent.Aldehydes and ketones (if not extremely sterically hindered) were reduced to the corresponding alcohols at room temperature mostly within 2-4 h in essentially quantitative yield. α,β-Unsaturated carbonyl compounds cleanly react in a 1,2-mode to afford the corresponding allylic alcohols. - Key Words: Reductions / Meerwein-Ponndorf-Verley reaction / Catalysis / Zirconium tetra-tert-butoxide / β-Hydride shift / Kinetics
- Knauer, Birgit,Krohn, Karsten
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p. 677 - 684
(2007/10/02)
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