Asymmetric hydrogenation of imines with chiral alkene-derived boron Lewis acids

2018 ◽  
Vol 16 (45) ◽  
pp. 8686-8689 ◽  
Author(s):  
Xiaoqin Liu ◽  
Ting Liu ◽  
Wei Meng ◽  
Haifeng Du
Keyword(s):  
Lewis Acids ◽  
Asymmetric Hydrogenation ◽  
Asymmetric Hydrogenations

Asymmetric hydrogenations of imines were realized by using readily available chiral alkene-derived Lewis acids to give up to 89% ee.

Iridium-catalyzed acid-assisted asymmetric hydrogenation of oximes to hydroxylamines

Science ◽  
2020 ◽  
Vol 368 (6495) ◽  
pp. 1098-1102 ◽  
Author(s):  
Josep Mas-Roselló ◽  
Tomas Smejkal ◽  
Nicolai Cramer
Keyword(s):  
Room Temperature ◽  
Asymmetric Hydrogenation ◽  
Selective Reduction ◽  
Building Blocks ◽  
Efficient Catalyst ◽  
Cyclopentadienyl Ligand ◽  
Acidic Conditions ◽  
Asymmetric Hydrogenations ◽  
Metal Catalyzed ◽  
Oxygen Bond

Asymmetric hydrogenations are among the most practical methods for the synthesis of chiral building blocks at industrial scale. The selective reduction of an oxime to the corresponding chiral hydroxylamine derivative remains a challenging variant because of undesired cleavage of the weak nitrogen-oxygen bond. We report a robust cyclometalated iridium(III) complex bearing a chiral cyclopentadienyl ligand as an efficient catalyst for this reaction operating under highly acidic conditions. Valuable N-alkoxy amines can be accessed at room temperature with nondetected overreduction of the N‒O bond. Catalyst turnover numbers up to 4000 and enantiomeric ratios up to 98:2 are observed. The findings serve as a blueprint for the development of metal-catalyzed enantioselective hydrogenations of challenging substrates.

Exploration of chiral diastereomeric spiroketal (SPIROL)-based phosphinite ligands in asymmetric hydrogenation of heterocycles

2020 ◽  
Vol 56 (60) ◽  
pp. 8432-8435
Author(s):  
Siyuan Sun ◽  
Pavel Nagorny
Keyword(s):  
Asymmetric Hydrogenation ◽  
Asymmetric Hydrogenations

New and readily available chiral SPIROL-based diphosphinite ligands (SPIRAPO) have been prepared and employed for iridium catalyzed asymmetric hydrogenations of quinolines, quinoxalines and 2H-1,4-bezoxazin-2-ones.

Asymmetric C–Heteroatom Bond Formation

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Asymmetric Catalysis ◽  
Covalent Binding ◽  
Asymmetric Hydrogenation ◽  
Lewis Base ◽  
State University ◽  
Asymmetric Allylation ◽  
Colorado State University ◽  
Asymmetric Hydrogenations ◽  
Reversible Covalent ◽  
The University

Tomislav Rovis at Colorado State University developed (Angew. Chem. Int. Ed. 2012, 51, 5904) an enantioselective catalytic cross-aza-benzoin reaction of aldehydes 1 and N-Boc imines 2. The useful α-amido ketone products 4 were configurationally stable under the reaction conditions. In the realm of asymmetric synthesis, few technologies have been as widely employed as the Ellman chiral sulfonamide auxiliary. Francisco Foubelo and Miguel Yus at the Universidad de Alicante in Spain have adapted (Chem. Commun. 2012, 48, 2543) this approach for the indium-mediated asymmetric allylation of ketimines 5, which furnished amines 6 with high diastereoselectivity. There has been vigorous research in recent years into the use of NAD(P)H surrogates, especially Hantzsch esters, for biomimetic asymmetric hydrogenations. Yong-Gui Zhou at the Chinese Academy of Sciences showed (J. Am. Chem. Soc. 2012, 134, 2442) that 9,10-dihydrophenanthridine (10) can also serve as an effective “H2” donor for the asymmetric hydrogenation of imines, including 7. Notably, 10 is used catalytically, with regeneration occurring under mild conditions via Ru(II)-based hydrogenation of the phenanthridine 11. A unique approach for asymmetric catalysis has been developed (Nature Chem. 2012, 4, 473) by Takashi Ooi at Nagoya University, who found that ion-paired complexes 14 could serve as effective chiral ligands in the Pd(II)-catalyzed allylation of α-nitrocarboxylates 12. The resulting products 13 are easily reduced to furnish α-amino acid derivatives. Another novel catalytic platform has been employed (J. Am. Chem. Soc. 2012, 134, 7321) for the chiral resolution of 1,2-diols 15 by Kian L. Tan at Boston College. Using the concept of reversible covalent binding, the catalyst 16 was found to selectively silylate a secondary hydroxyl over a primary one, thus leading to the enantioenriched products 17 and 18. Scott E. Denmark at the University of Illinois has applied (Angew. Chem. Int. Ed. 2012, 51, 3236) his chiral Lewis base strategy to the enantioselective vinylogous aldol reaction of N-silyl vinylketene imines 19 to produce γ-hydroxy-α,β-unsaturated nitriles 22. For the preparation of enantioenriched homopropargylic alcohols 25, the asymmetric addition of allenyl metal nucleophiles (e.g., 24) to aldehydes 23 provides a straightforward approach.

Adsorption and stability of chiral modifiers based on 1-(1-naphthyl)-ethylamine for Pt catalysed heterogeneous asymmetric hydrogenations

2015 ◽  
Vol 5 (2) ◽  
pp. 705-715 ◽  
Author(s):  
Fabian Meemken ◽  
Titian Steiger ◽  
Mareike C. Holland ◽  
Ryan Gilmour ◽  
Konrad Hungerbühler ◽  
...  
Keyword(s):  
Asymmetric Hydrogenation ◽  
Pt Catalyst ◽  
Spectroscopic Investigations ◽  
Mechanistic Insight ◽  
Asymmetric Hydrogenations ◽  
Ir Spectroscopic

Catalytic and in situ ATR-IR spectroscopic investigations provide mechanistic insight relevant to heterogeneous asymmetric hydrogenation on Pt catalyst using naphthylethylamine-based modifiers.

Asymmetric Hydrogenation of Benzalacetone Catalyzed by RuCl2 (TPPTS) 2-(S,S)-DPENDS in Water Medium

2010 ◽  
Vol 31 (3) ◽  
pp. 273-277
Author(s):  
Jinbo WANG ◽  
Ruixiang QIN ◽  
Wei XIONG ◽  
Yun JIA ◽  
Derong LIU ◽  
...  
Keyword(s):  
Asymmetric Hydrogenation ◽  
Water Medium

Reaction Mechanisms of Inorganic and Organometallic Systems

2007 ◽  
Author(s):  
Robert B. Jordan
Keyword(s):  
Electron Transfer ◽  
Heterogeneous Systems ◽  
Asymmetric Hydrogenation ◽  
Pressure Effects ◽  
General Level ◽  
Hydrogenation Catalysts ◽  
Methyl Transferase ◽  
Transfer Region ◽  
Previous Edition ◽  
Oxide Synthase

This third edition retains the general level and scope of earlier editions, but has been substantially updated with over 900 new references covering the literature through 2005, and 140 more pages of text than the previous edition. In addition to the general updating of materials, there is new or greatly expanded coverage of topics such as Curtin-Hammett conditions, pressure effects, metal hydrides and asymmetric hydrogenation catalysts, the inverted electron-transfer region, intervalence electron transfer, photochemistry of metal carbonyls, methyl transferase and nitric oxide synthase. The new chapter on heterogeneous systems introduces the basic background to this industrially important area. The emphasis is on inorganic examples of gas/liquid and gas/liquid/solid systems and methods of determining heterogeneity.

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