Article
Chemistry, Multidisciplinary
Chenhao Zhang, Anthony Z. Gao, Xin Nie, Chen-Xi Ye, Sergei I. Ivlev, Shuming Chen, Eric Meggers
Summary: This study demonstrates the catalytic deracemization of ketones with alpha-stereocenters in a single reaction through photoredox deprotonation and enantioselective protonation. By utilizing a photoredox catalyst and a tertiary amine, nonracemic carbonyl compounds with up to 97% enantiomeric excess can be obtained. This light-driven strategy provides a blueprint for deracemizations of common carbonyl compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Changhua Song, Hong-Hao Zhang, Shouyun Yu
Summary: In this study, a decarboxylative allylic benzylation catalyzed by Pd/photoredox in a regio- and enantioselective manner is achieved. This method uses readily available aryl acetic acids as benzylic nucleophile equivalents without preactivation. The mild and atom-economical protocol expands the scope of coupling partners of allylic electrophiles. Additionally, vinyl epoxides can undergo this transformation smoothly, producing various chiral homoallylic alcohols bearing all-carbon quaternary stereocenters.
Article
Chemistry, Physical
Qian Zeng, Fengyun Gao, Jordi Benet-Buchholz, Arjan W. Kleij
Summary: A modular and practical method has been developed for the synthesis of complex allylic alcohols through a three-component reaction using dual photoredox/Ni catalysis. This method allows for high regio- and stereoselectivity and provides access to compounds with sterically congested and functionalized quaternary carbon centers. The stereoselectivity can be reversed by changing the photocatalyst.
Article
Chemistry, Organic
Marina Briand, Linh D. Thai, Flavien Bourdreux, Nicolas Vanthuyne, Xavier Moreau, Emmanuel Magnier, Elsa Anselmi, Guillaume Dagousset
Summary: Site-selective trifluoromethylation of silyl dienol ethers derived from alpha,ss-unsaturated aldehydes, ketones, and amides was achieved for the first time in the remote gamma position. An unprecedented enantioselective C(sp(3))-H perfluoroalkylation process is disclosed.
Article
Chemistry, Multidisciplinary
Kun Liu, Armido Studer
Summary: This study presents a method for the formal beta-C-H arylation of aldehydes and ketones using cooperative nickel and photoredox catalysis, which exhibits wide scope and tolerance towards functional groups. Additionally, it enables beta-alkenylation, beta-alkynylation, and beta-acylation of aldehydes under similar conditions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(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
Suresh Kumar, Markus Lange, You Zi, Helmar Goerls, Ivan Vilotijevic
Summary: Using silylated compounds as latent pronucleophiles allows for the enantioselective allylation of common stabilized C-nucleophiles with allylic fluorides, overcoming the limitations of Lewis base catalyzed allylations.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Wenke Dong, Zhiyang Ye, Wanxiang Zhao
Summary: Catalytic asymmetric hydroboration of ketone-derived silyl enol ethers using cobalt catalyst has been reported, providing a convenient approach to access valuable enantiopure beta-hydroxy boronic esters. This method features mild reaction conditions, a broad substrate scope, and excellent enantioselectivities, making it potential to streamline the synthesis of complex molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Kevin Ng, Michael Khoury, Thomas Gerard Minehan
Summary: Total syntheses of sesquiterpenes (+)-sootepdienone, (-)-jambolanin C, (-)-jambolanin I, and (-)-gibberodione have been achieved in 10 steps each from R-(+)-pulegone, allowing determination of the absolute configuration of the natural products. A key step in the synthetic pathways involves the one-carbon ring expansion of a cyclic allylic phosphonate to a substituted cycloheptenone through a tandem oxidative cleavage/intramolecular Horner-Wadsworth-Emmons reaction.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Physical
Xiaowu Fang, Songwei Wen, Peishen Jin, Wenjing Bao, Shanshan Liu, Hengjiang Cong, Xiao Shen
Summary: Fluorinated enol silanes are widely used in synthetic transformations, but previous methods only allowed for the synthesis of racemic products. In this study, an enantioselective reductive coupling reaction was developed to access enantioenriched fluorinated enol silanes. The practicality of this methodology was demonstrated through multistep-one-isolation processes, and the synthetic potential of enantioenriched fluorinated enol silanes in the synthesis of valuable chiral organofluorine compounds was also shown.
Article
Chemistry, Multidisciplinary
Giacomo E. M. Crisenza, Adriana Faraone, Eugenio Gandolfo, Daniele Mazzarella, Paolo Melchiorre
Summary: Enantioselective catalytic processes can be achieved by using visible light to alter the reactivity of chiral iridium complexes, enabling new mechanistic pathways. Photoexcitation induces a redox event that unlocks difficult-to-realize reactions, such as enantioselective alkyl-alkyl cross-coupling between allylic alcohols and radical precursors.
Article
Chemistry, Physical
Meng-Yuan Dong, Chun-Yu Han, Dong-Sheng Li, Yang Hong, Fang Liu, Hong-Ping Deng
Summary: In this study, a mild and operationally simple approach for allylic C(sp(3))-H alkylation without oxidants was developed through the triplet synergistic merger of Brønsted base/cobalt/photoredox catalysis. This strategy enables the direct allylic C(sp(3))-H alkylation of various branched alpha-olefins with protic C(sp(3))-H feedstocks.
Article
Chemistry, Organic
Hao Xu, Xufeng Li, Yuzheng Dong, Shuangran Ji, Junze Zuo, Jian Lv, Daoshan Yang
Summary: An efficient strategy for the preparation of aryl phosphonates has been demonstrated via a blue-light-promoted single electron transfer process of an EDA complex. The method enables the construction of aryl phosphonates through the indirect C-H functionalization of arenes, leading to good to excellent yields of substituted aryl phosphonates and the recovery and reuse of the byproduct thianthrene. This approach has potential application value in drug discovery and development.
Article
Biochemistry & Molecular Biology
Dmitry A. Dulov, Alexey V. Bogdanov, Sergey G. Dorofeev, Tatiana V. Magdesieva
Summary: An inexpensive and highly efficient metal-free alternative catalyst was proposed for the alkylation of silyl enol ethers, showing superior activity to iridium phenylpyridyl complex in photoredox reactions. The catalyst, 2,7-di-tert-butyl-5,10-bis(4-trifluoromethylphenyl)-5,10-dihydrophenazine, demonstrated excellent properties for photoredox catalysis, including long-lived triplet excited state, strong reducing ability, and high stability. The catalyst could be easily obtained from diaryl amines through a one-pot synthetic procedure.
Article
Chemistry, Organic
Natalie C. Dwulet, Vincenzo Ramella, Christopher D. Vanderwal
Summary: Soft enolization conditions are shown to be more efficient than hard enolization protocols in regioselectively forming enoxysilanes from unsymmetrical 3-substituted cycloalkanones. The regioselectivities achieved are complementary to those obtained from cycloalkenone conjugate addition/enolate silylation with high selectivity.
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)
Article
Chemistry, Organic
Kohsuke Ohmatsu, Ryuhei Suzuki, Hiroki Fujita, Takashi Ooi
Summary: In this study, a photoinduced catalytic C(sp3)-H alkylation of benzylic fluorides was developed. The use of zwitterionic 1,2,3-triazolium amidate as a hydrogen-atom transfer catalyst proved uniquely effective for promoting this transformation, enabling 1,1-difunctionalization of benzylic fluorides and providing rapid access to a variety of functionalized molecular entities.
Article
Chemistry, Organic
Kohsuke Ohmatsu, Ryuhei Suzuki, Hiroki Fujita, Takashi Ooi
Summary: The chemical and physical properties of amides are significantly influenced by the electron-withdrawing groups attached to the nitrogen atom. In this study, the superior performance of N-diphenylphosphinyl 1,2,3-triazolium amidate as a photoinduced hydrogen-atom transfer catalyst is reported, compared to its N-benzoyl analog. The binary catalyst system of the phosphinyl amidate and an Ir-based photocatalyst enables the alkylation of unbiased C-H bonds.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
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
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)