Article
Chemistry, Organic
Shuma Sasaki, Jun Kikuchi, Shingo Ito, Naohiko Yoshikai
Summary: In this study, a method for preparing stereodefined enolates by leveraging the stereoselective oxyfunctionalization of unactivated alkynes and their reaction with aldehydes to form γ,δ-unsaturated β-diketones was described.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Stuart C. D. Kennington, Saul F. Teloxa, Miguel Mellado-Hidalgo, Oriol Galeote, Sabrina Puddu, Marina Bellido, Pedro Romea, Felix Urpi, Gabriel Aullon, Merce Font-Bardia
Summary: A direct and asymmetric aldol reaction of N-acyl thiazinanethiones with aromatic aldehydes catalyzed by chiral nickel(II) complexes was reported. The reaction gives high yields of O-TIPS-protected anti-aldol adducts with remarkable stereocontrol and atom economy. The removal of the achiral scaffold provides enantiomerically pure intermediates with synthetic interest for producing anti-alpha-amino-beta-hydroxy and alpha,beta-dihydroxy carboxylic derivatives, with theoretical calculations explaining the observed high stereocontrol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Teng Yuan, Kelton Radefeld, Chuan Shan, Carter Wegner, Erin Nichols, Xiaohan Ye, Qi Tang, Lukasz Wojtas, Xiaodong Shi
Summary: Here, we have reported an intermolecular asymmetric hydrative aldol reaction by using a vinyl-gold intermediate under ambient conditions. This reaction provides a base-free approach to β-hydroxy amides with high efficiency, yielding up to 95% and with over 50 examples. The use of vinyl gold intermediate as a reactive nucleophile and Fe(acac)(3) as a critical co-catalyst prevents undesired protodeauration, allowing the transformation to proceed under mild conditions with excellent functional group tolerance and stereoselectivity (>20:1 d.r. and up to 99% ee).
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Multidisciplinary
Johannes Grosskopf, Thorsten Bach
Summary: Upon irradiation with a suitable chiral catalyst, racemic compounds can be converted into enantiopure compounds through a process called photochemical deracemization. This review comprehensively covers the research and current developments in this field, discussing the reactions and mechanistic details underlying the presented reaction. Photochemical deracemization offers a unique opportunity to directly obtain enantiopure compounds from racemates, and short-lived intermediates play a key role in determining the enantioselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Nanoscience & Nanotechnology
Miguel Sanchez-Fuente, Alberto Lopez-Magano, Alicia Moya, Ruben Mas-Balleste
Summary: Condensation of BINAPO-(PhCHO)(2) and 1,3,5-tris(4-aminophenyl)benzene(TAPB) leads to a new imine-based chiral organic material (COM) that can be post-functionalized through reductive transformation of imine linkers to amines. Although the imine-based material is not stable enough to be used as a heterogeneous catalyst, the reduced amine-linked framework can be efficiently utilized in asymmetric allylation of various aromatic aldehydes. The obtained yields and enantiomeric excesses are comparable to those observed for the molecular BINAP oxide catalyst, with the added advantage of recyclability offered by the amine-based material.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Mariia Babkova, Rene Wilhelm
Summary: In this study, a series of new multifunctional organocatalysts were prepared and evaluated for the asymmetric aldol reaction of acetone and aromatic aldehydes. Several of the catalysts exhibited high catalytic activity and selectivity. The combination of camphor-based moiety and proline-based unit was found to be crucial for the performance of the catalysts.
Article
Chemistry, Organic
Florian Livernaux, Sidonie Lavieville, Pascale Guiffrey, Jean-Marc Campagne, Eric Leclerc
Summary: The enantioselective addition of difluoroenoxysilanes to aromatic aldehydes, catalyzed by cationic palladium aqua complexes, was achieved. The reaction is easy to carry out, does not require anhydrous conditions, and can be performed at room temperature. The palladium catalysts, previously discovered and reported by Sodeoka, can be prepared in two steps from PdCl2(MeCN)(2). The aldol compounds were obtained in good yields and with enantiomeric ratios up to 93 : 7, with higher efficiency observed using electron-rich aldehydes.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Isaac G. Sonsona, Andrea Vicenzi, Marco Guidotti, Giorgiana Denisa Bisag, Mariafrancesca Fochi, Raquel P. Herrera, Luca Bernardi
Summary: The study demonstrates the improved selectivity of an asymmetric aldol reaction by replacing part of the catalyst, and identifies the most suitable reaction conditions. However, these conditions seem to be limited to oxindoles bearing a 3-substituent of funapide.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Julian Baars, Isabelle Grimm, Dirk Blunk, Joerg-Martin Neudoerfl, Hans-Guenther Schmalz
Summary: A 12-step total synthesis of the natural product dysiherbol A was achieved, revealing the need for revision of the originally proposed structure and absolute configuration. The synthesis involved key steps including Cu-catalyzed addition/enolate-trapping, Au-catalyzed double cyclization, and late installation of the C5-bridgehead methyl group. Spectroscopic measurements confirmed the identity of the synthetic compound with the natural product but with an opposite molecular rotation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Guanghao Huang, Regis Guillot, Cyrille Kouklovsky, Boris Maryasin, Aurelien de la Torre
Summary: A broadly applicable diastereo- and enantioselective inverse-electron-demand Diels-Alder reaction of 2-pyrones and acyclic enol ethers is reported, leading to the synthesis of bridged bicyclic lactones with high yields and enantioselectivities using a copper(II)-BOX catalytic system. Mechanistic studies suggest a stepwise mechanism, and the synthetic potential of the bridged bicyclic lactones is demonstrated through the enantioselective synthesis of polyfunctional cyclohexenes and cyclohexadienes, as well as a carbasugar unit.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Qinglin Zhang, Kang Liang, Chang Guo
Summary: A novel electrolytic system has been introduced to divert standard ionic reactivity, providing a brand-new pattern of reactivity-electricity-driven asymmetric catalysis, which serves as a privileged chiral platform for enantioselective radical allylation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Peng Zhang, Qi Xu, Xiao-Mei Wang, Jia Feng, Chuan-Jun Lu, Yingzi Li, Ren-Rong Liu
Summary: The first enantioselective synthesis of N-N bisindole atropisomers via palladium-catalyzed construction of one indole skeleton is reported in this study. A wide variety of N-N axially chiral bisindoles were generated with good yields and excellent enantioselectivities through a cascade condensation/N-arylation reaction. The reaction mechanism and enantiocontrol were further investigated using density functional theory (DFT) calculations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Ken-Loon Choo, Bijan Mirabi, Karl Z. Demmans, Mark Lautens
Summary: Enantioenriched spiro-oxiranes with three contiguous stereocenters were synthesized using a rhodium-catalyzed cascade reaction, enabling the formation of a spirocyclic framework in a single step. Both sp(2)- and sp-hybridized carbon nucleophiles were found to be efficient initiators, yielding products with different functional groups. Derivatization studies demonstrated the synthetic versatility of the products' epoxide and alkyne moieties. DFT calculations were employed to explain spectroscopic discrepancies between solution- and solid-state structures of the products.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Liangliang Zhang, Martin Oestreich
Summary: The passage describes a reaction sequence involving enantioselective copper-catalyzed conjugate silylation and diastereotopic group-selective aldol cyclization. The intramolecular aldol reaction's diastereoselectivity depends on the silicon nucleophile used, and the more basic zinc reagent enables thermodynamically driven cis-to-trans isomerization. A wide range of electron-withdrawing groups, including electron-deficient heterocycles, are compatible with the different procedures developed.
Article
Chemistry, Multidisciplinary
Saul F. Teloxa, Miguel Mellado-Hidalgo, Stuart C. D. Kennington, Pedro Romea, Felix Urpi, Gabriel Aullon, Merce Font-Bardia
Summary: A direct and asymmetric aldol reaction between N-azidoacetyl-1,3-thiazolidine-2-thione and aromatic aldehydes catalyzed by a chiral nickel(II)-Tol-BINAP complex has been developed. The reaction gives anti alpha-azido-beta-silyloxy adducts with excellent stereocontrol and high yields. The removal of thiazolidinethione allows for the synthesis of a wide array of enantiomerically pure derivatives, providing a new route to di- and tripeptide blocks containing a beta-aryl-beta-hydroxy-alpha-amino acid.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Tsubasa Nakashima, Haruka Fujimori, Kohsuke Ohmatsu, Takashi Ooi
Summary: Intermediary radical cations, generated through single-electron oxidation of enol silyl ethers by excited Ir-based photocatalysts, are exploited as Bronsted acids for activating heteroarylcyanides. This enables the direct allylic C-H heteroarylation of enol silyl ethers under visible-light irradiation.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Kohsuke Ohmatsu, Yusuke Morita, Mari Kiyokawa, Takashi Ooi
Summary: The stereoselective cyanoalkylation of electron-deficient olefins with potassium cyanide and alkyl halides was developed using modular chiral 1,2,3-triazolium salts as catalysts with hydrogen bond-donor ability. The reaction involves enantioselective conjugate addition of a cyanide ion and consecutive diastereoselective alkylation of intermediary chiral triazolium enolates controlled by the catalyst. Properly tuned chiral triazolium ion as a catalyst and the presence of cyano functionality in the enolate are crucial for achieving high levels of acyclic stereocontrol.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Organic
Kohsuke Kato, Daisuke Uraguchi, Takashi Ooi
Summary: A new o-QM catalyst was developed for the dehydridative oxidation of benzylic alcohols. The introduction of an overcrowded olefinic component into o-QM induced structural distortion, beneficial for imparting triarylmethylium character and regenerability. The zwitterionic resonance form of o-QM generated through photoexcitation and relaxation exhibited dehydridation activity.
Article
Chemistry, Multidisciplinary
Kohsuke Ohmatsu, Haruka Fujimori, Kodai Minami, Kosuke Nomura, Mari Kiyokawa, Takashi Ooi
Summary: Thioamidate ions are introduced as competent cocatalysts for multisite proton-coupled electron transfer catalysis. The high pK(a) values of their conjugate acids contribute to the effectiveness of these anions. The combined use of stable tetrabutylammonium thioamidate and an appropriate Ir-based photosensitizer enables the C-H alkylation of various C-H donors, including simple cyclic alkanes, under visible-light irradiation.
Article
Chemistry, Physical
Kodai Minami, Kohsuke Ohmatsu, Takashi Ooi
Summary: An unconventional cooperative catalysis for hydrogen-atom-transfer-mediated acceptorless dehydrogenative cross-coupling is described in this study. By using specific catalysts, C-H/C-H cross-couplings between heteroatom-containing C-H donors and enamides or 1,1-diarylethenes were achieved under visible-light irradiation without the need for oxidants, hydrogen evolution catalysts, or electrodes. The key to this catalysis is the susceptibility of the conjugate acid of the triazolium amidate, amide triazolium, to single-electron reduction to complete the catalytic cycle.
Article
Chemistry, Organic
Kohsuke Ohmatsu, Yusuke Morita, Mari Kiyokawa, Kimihiro Hoshino, Takashi Ooi
Summary: A catalytic asymmetric Strecker reaction of ketoimines with potassium cyanide (KCN) has been developed, utilizing a chiral 1,2,3-triazolium ion as a catalyst in combination with a protic additive. Control experiments revealed the involvement of a retro-Strecker reaction, leading to decreased product yield and enantioselectivity. This approach allows for highly efficient and enantioselective cyanide addition to various ketoimines.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Review
Chemistry, Organic
Daisuke Uraguchi, Takashi Ooi
Summary: The study demonstrates the control of multiple selectivity using P-spiro chiral tetraaminophosphonium ion, including enantioselectivity, geometry, regiochemistry, diastereomer formation, and reaction pathway. Theoretical investigation reveals key elements for achieving multiple selectivity control.
JOURNAL OF SYNTHETIC ORGANIC CHEMISTRY JAPAN
(2021)
Article
Chemistry, Multidisciplinary
Hong Yi, Kimberly M. Osten, Tetyana Levchenko, Alex J. Veinot, Yoshitaka Aramaki, Takashi Ooi, Masakazu Nambo, Cathleen M. Crudden
Summary: A series of chiral Au-13 nanoclusters were successfully synthesized and characterized, exhibiting high luminescence and stability. This opens up opportunities for further investigation into the impact of chirality on the properties of these clusters.
Article
Chemistry, Multidisciplinary
Daisuke Uraguchi, Kohsuke Kato, Takashi Ooi
Summary: An o-quinone methide (o-QM) with an overcrowded olefinic framework is introduced, showing dehydridation activity due to its enhanced zwitterionic character, especially under photoexcitation. Experimental analysis and density functional theory calculations provide mechanistic insights, revealing that the o-QM operates in dehydridative catalysis for the oxidation of benzylic secondary alcohols.
Article
Chemistry, Organic
Yuto Kimura, Daisuke Uraguchi, Takashi Ooi
Summary: The protocol described enables a highly stereoselective [3 + 2]-cycloaddition of cyclopropylurea with alpha-substituted acrylates, leading to the efficient synthesis of a variety of stereochemically defined 5-membered alicyclic alpha-quaternary beta-amino acids, which are useful building blocks for beta-peptides and peptidomimetics.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Organic
Tsubasa Nakashima, Kohsuke Ohmatsu, Takashi Ooi
Summary: The collaboration between an Ir-based photosensitizer with mild oxidizing ability and a thiol catalyst enables efficient allylic C-H functionalization of enol silyl ethers with imines under visible light irradiation. Subsequent transformations of the aminoalkylated enol silyl ethers allow for the facile construction of unique molecular frameworks such as functionalized octahydroisoindol-4-one.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
