Article
Polymer Science
Mohammad Yasir, Andreas F. M. Kilbinger
Summary: Norbornene and cyclohexene show different polymerization behaviors using Grubbs' catalysts due to their varying ring strain energy levels; a sequence-selective cascade polymerization of a monomer containing both rings resulted in polymers with moderate molecular weight dispersities and good control over molecular weight.
Review
Chemistry, Multidisciplinary
Bokun Li, Chenyang Hu, Xuan Pang, Xuesi Chen
Summary: This Review provides an overview of a redox-controlled switchable strategy for controlled synthesis of polymers. By developing valence-variable metal-based catalysts, high sequence-control and easy-handling in ring-opening (co)polymerizations can be achieved, resulting in polymer products with desired microstructures and practical performances.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
Article
Chemistry, Organic
Vachiraporn Ajavakom, Potchanee Pandokrak, Sofia S. Salim, Gamal A. I. Moustafa, Richard K. Bellingham, Joseph T. Hill-Cousins, Anawat Ajavakom, Richard C. D. Brown
Summary: A ring-closing metathesis (RCM) reaction of monobrominated dienes using Grubbs II catalyst was reported, giving moderate to good yields (40-80%) of seven-membered bromoolefins. Attempts to form five-, six-, or eight-membered bromoolefins through RCM were unsuccessful, except for one example that resulted in the formation of a bromomethyl-substituted cyclohexene as a byproduct. The selected bromoolefin RCM products showed utility in Suzuki-Miyaura reactions. Vinylic halide exchange (Br -> Cl) was observed as a side reaction under RCM conditions.
Article
Chemistry, Multidisciplinary
Nils Ansmann, Thaddaus Thorwart, Lutz Greb
Summary: The Lewis superacid bis(perchlorocatecholato)silane catalyzes C-O bond metathesis of alkyl ethers with high efficiency, enabling chemoselective ring contractions of macrocyclic crown ethers and unprecedented ring-closing metathesis of polyethylene glycols for polymer-selective degradation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Polymer Science
Nicholas M. M. Shawver, Alicia M. M. Doerr, Brian K. K. Long
Summary: A polymer's properties are determined by the monomers used and the way they are assembled. Polyesters have gained attention as biodegradable alternatives to other petrochemical-based polymers. Researchers have developed redox-switchable catalysts that can alter chemoselectivity and kinetic modulation in ring-opening polymerizations.
JOURNAL OF POLYMER SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Myron Triantafyllakis, Sam Alexander, Sophie Woolford, Claire Wilson, J. Stephen Clark
Summary: The fully functionalized A-F fragment of the Pacific ciguatoxin CTX3C has been synthesized using specific reaction sequences and synthesis routes, achieving the construction of a multi-ring system and the introduction of functional groups.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Dmitry S. Belov, Gabriela Tejeda, Charlene Tsay, Konstantin V. Bukhryakov
Summary: Vanadium-based catalysts have been demonstrated to catalyze ring-closing olefin metathesis reactions by well-defined V chloride alkylidene phosphine complexes, exhibiting good functional group tolerance. The properties of the imido group and phosphine were found to play a crucial role in the stability of active intermediates.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Nasrin Jahan, Arijit Das, Inul Ansary
Summary: In this study, a simple method for cross-aldol condensation reaction was developed to synthesize two types of compounds, and a series of dibenzo-fused macrocycles were obtained through ring-closing metathesis reaction. The cis/trans configurations of the products were confirmed by H-1-NMR spectral data.
Article
Chemistry, Organic
Frank Schmidt, Aparna Viswanathan Ammanath, Friedrich Goetz, Martin E. Maier
Summary: A new synthesis route was established for the macrolactone antibiotic berkeleylactone A. The synthesis involved ring-closing alkyne metathesis (RCAM) of an ester substrate with 1-propynyl termini. The carboxylic part of the substrate was assembled using alkyne chemistry, while the alcohol part of the ester was synthesized through propylene oxide opening and triple bond migration reactions. After successful RCAM, the triple bond was selectively hydrogenated and the 4,5-diol was oxidized to obtain the desired derivative. The thioether formation and reduction of the 8,9-double bond were also achieved. However, the antimicrobial activity of the analog was found to be slightly reduced.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Andrea Ojeda-Porras, Remi Aouzal, Claire Wilson, Joelle Prunet
Summary: Two synthetic routes for the ABC tricycle of Taxol are presented, both involving a relay ring-closing metathesis reaction to form the central B ring. In the first approach, the extender arm is positioned on the A ring, while the C ring bears the relay tether in the second route. Despite the efficient synthesis of metathesis precursors with diverse extender arms, the crucial metathesis reactions failed to yield the target compounds in all cases.
Article
Chemistry, Multidisciplinary
Boris Lozhkin, Thomas R. Ward
Summary: An efficient method for synthesizing monosubstituted aromatic compounds is presented, utilizing ring-closing metathesis followed by spontaneous 1,2-elimination. The method shows high efficiency for late-stage functionalization in various solvents (up to 920 TON) and is compatible with strained cycles and other multiple bonds in the substrate.
HELVETICA CHIMICA ACTA
(2021)
Article
Chemistry, Multidisciplinary
Sambasivarao Kotha, Deepshikha Singh, Vijayalakshmi Bandi
Summary: An efficient and short synthetic sequence for highly functionalized urazole derivatives has been reported. N-substituted-1,2,4-triazoline-3,5-dione (TAD) was used as a versatile synthetic reagent. Simple reactions including allylation, ring-closing metathesis, and hydrogenation were successfully employed to construct oxygenated urazole derivatives, which may have implications in medicinal chemistry and organic synthesis.
Article
Chemistry, Multidisciplinary
Ammundi Jayavel Chirranjeevi Padmashrija, Sathananthan Kannadasan, Ponnusamy Shanmugam
Summary: A convenient and efficient synthesis of 3-spiro cycloalkene fused 7-aza-2-indalones has been achieved via ring-closing metathesis (RCM) using Grubbs-II catalyst from 3,3'-di- or N,3,3'-tri-allyl/homoallyl/pentenyl 7-aza-2-indalones. The reaction scope was demonstrated by synthesizing spiro products of various ring sizes (n=5, 7, and 18) with different alkenylation agents as substrates. In addition to typical RCM products, a cross metathesis (CM) product and a macrocyclic, 18-membered bis-spirodiene were also observed.
Article
Chemistry, Physical
Valerio Sabatino, Dario Staub, Thomas R. Ward
Summary: The synthesis of N-substituted indoles via ring-closing metathesis of indole precursors with N-terminal alkenes was reported. Good yields (up to 72%) were achieved in aqueous metathesis using commercial catalysts or artificial metalloenzymes. Furthermore, the presence of a second metathesis substrate increased the yield of N-acetylindole.
Review
Chemistry, Organic
Santhosh Kumar Podiyanachari, Hassan S. Bazzi, Mohammed Al-Hashimi
Summary: Synthesis of cycloolefin-based polymers via metathesis-accompanied cyclopolymerization and tandem ring-opening/ring-closing metathesis (RO/RCM) polymerization leads to highly functional cycloolefin ring-based polymers.
CURRENT ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Yuyang Dong, Kwangmin Shin, Binh Khanh Mai, Peng Liu, Stephen L. Buchwald
Summary: This paper reports an asymmetric olefin hydromethylation protocol enabled by CuH catalysis, in which methyl tosylate is used as a methyl source and iodide ion converts it into the active reactant methyl iodide. The method demonstrates broad applicability and tolerance.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Edward Miller, Binh Khanh Mai, Jacquelyne A. Read, William C. Bell, Jeffrey S. Derrick, Peng Liu, F. Dean Toste
Summary: Developing strategies to study reactivity and selectivity in flexible catalyst systems has become an important topic of research. In this study, a combined experimental and computational approach was used to investigate the mechanistic role of an achiral DABCOnium cofactor in a regio- and enantiodivergent bromocyclization reaction. It was found that electron-deficient aryl substituents resulted in rigidified transition states, driving the selectivity of the reaction, while electron-rich aryl groups led to more flexible transition states, where interactions between the catalyst and substrate were more important.
Article
Chemistry, Multidisciplinary
Ruihan Wang, Yidong Wang, Ruiqi Ding, Parker B. Staub, Christopher Z. Zhao, Peng Liu, Yi-Ming Wang
Summary: A newly-developed cationic cyclopentadienyliron dicarbonyl complex enables the conversion of propylene to its allylic C-C bond coupling products under catalytic conditions. This approach is also applicable to the allylic functionalization of simple alpha-olefins with distinctive branched selectivity. Experimental and computational studies reveal the allylic deprotonation of the metal-coordinated alkene as the turnover-limiting step and provide insights into the multifaceted roles of the newly designed ligand in promoting allylic C-H functionalization with enhanced reactivity and stereoselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Tobias Koengeter, Can Qin, Binh Khanh Mai, Qinghe Liu, Yucheng Mu, Peng Liu, Amir H. Hoveyda
Summary: This paper presents a stereoretentive strategy for catalytic cross-metathesis reaction between tri-, Z- or E-di, or monosubstituted olefins and Z- or E-2-bromo-2-butene, leading to the formation of various trisubstituted alkenyl bromides. The method is applicable for the generation of products containing polar moieties or sterically hindered alkenes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Amit Kumar Simlandy, Turki M. Alturaifi, Johny M. Nguyen, Lucas J. Oxtoby, Quynh Nguyen Wong, Jason S. Chen, Peng Liu, Keary M. Engle
Summary: We report a transient directing group (TDG) strategy for site-selective palladium-catalyzed reductive Heck-type hydroalkenylation and hydroalkynylation of alkenylaldehydes using alkenyl and alkynyl bromides. This strategy allows for the construction of a stereocenter at the delta-position with respect to the aldehyde. Computational studies reveal the beneficial roles of rigid TDGs, such as L-tert-leucine, in promoting TDG binding and inducing high levels of enantioselectivity in alkene insertion.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Hui-Qi Ni, Malkanthi K. Karunananda, Tian Zeng, Shenghua Yang, Zhen Liu, K. N. Houk, Peng Liu, Keary M. Engle
Summary: Multistep organic synthesis allows the conversion of simple chemical feedstocks into more complex products with specific functions. This study introduces a novel approach to organic reactions that can generate multiple valuable products with different carbon skeletons in a single operation. Through a palladium-catalyzed reaction, a single alkene starting material can be converted into two structurally distinct products, demonstrating the potential for simultaneous access to diverse compounds. The findings of this study provide insights into the mechanistic details of this unique catalytic system and establish a new method for small-molecule library synthesis.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Jingfeng Huo, Yue Fu, Melody J. Tang, Peng Liu, Guangbin Dong
Summary: In this research, the first nickel-catalyzed Catellani-type annulation of aryl triflates and chlorides was achieved to form various benzocyclobutene-fused norbornanes in high efficiency. Mechanistic studies revealed an unexpected outer-sphere concerted metalation/deprotonation pathway and the essential roles of the base and the triflate anion. Compared to palladium catalysis, the reaction showed a broad functional group tolerance and enhanced regioselectivity.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Huiling Shao, Victor Adebomi, Angele Bruce, Monika Raj, Kendall N. Houk
Summary: This study involves a computational investigation of CyClick chemistry, a reaction that selectively forms cyclic peptides from linear peptide aldehydes without the use of catalysts or directing groups. The research explores the role of intramolecular hydrogen bonds (IMHBs) in promoting the reaction mechanism and highlights the importance of IMHBs in stabilizing intermediate states and controlling product stereoselectivity. The study also examines the effect of ring strain energy on the reaction, finding that low ring strain energy promotes the formation of more stable cyclic peptides.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Jicheng Wu, Peijing Jia, Rositha Kuniyil, Peng Liu, Weiping Tang
Summary: In this study, we report an efficient method for the stereoselective synthesis of challenging α-linked glycoconjugates using a Rh-II/chiral phosphoric acid (CPA)-cocatalyzed dynamic kinetic anomeric O-alkylation. By exploring various parameters of the cocatalytic system, we achieved excellent anomeric selectivity, excellent diastereoselectivity, broad substrate scope, and high efficiency for this glycosylation reaction. DFT calculations suggested that the anomeric selectivity was determined by steric interactions between the C2-carbon of the carbohydrate and the phenyl group of the metal carbenoid, while diastereoselectivity at the newly generated stereogenic center was influenced by π-π interactions with the C2-OBn substituent on the carbohydrate substrate.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Dennis A. Kutateladze, Binh Khanh Mai, Yuyang Dong, Yu Zhang, Peng Liu, Stephen L. Buchwald
Summary: A copper hydride-catalyzed approach has been developed for the synthesis of Z-configured trisubstituted alkenes with high stereo- and regioselectivity. This method provides a valuable strategy for accessing challenging classes of alkenes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Benjamin G. Hejna, Jacob M. Ganley, Huiling Shao, Haowen Tian, Jonathan D. Ellefsen, Nicholas J. Fastuca, Kendall N. Houk, Scott J. Miller, Robert R. Knowles
Summary: We present a highly enantioselective radical-based hydroamination of enol esters with sulfonamides using an Ir photocatalyst, Bronsted base, and tetrapeptide thiol. The reaction produces 23 protected β-amino-alcohol products with selectivities up to 97:3 er. Experimental and computational studies reveal that hydrogen bonding, π-π stacking, and London dispersion interactions play important roles in substrate recognition and enantioinduction.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Lei Cheng, Dian Li, Binh Khanh Mai, Zhiyu Bo, Lida Cheng, Peng Liu, Yang Yang
Summary: The merger of photoredox catalysis and PLP biocatalysis enables the development of a new synthetic method for preparing valuable noncanonical amino acids, allowing controlled formation of chiral products.
Article
Multidisciplinary Sciences
Huamin Wang, Huiling Shao, Ankita Das, Subhabrata Dutta, Hok Tsun Chan, Constantin Daniliuc, K. N. Houk, Frank Glorius
Summary: In this study, a photoinduced ring enlargement method of thiophenes was developed, which involves the insertion of bicyclo[1.1.0]butanes to form eight-membered bicyclic rings under mild conditions. The synthetic value, broad functional-group compatibility, and excellent chemo- and regioselectivity were demonstrated by scope evaluation and product derivatization. Experimental and computational studies suggested a photoredox-induced radical pathway.
Article
Chemistry, Physical
Wenzhen Fu, Natalia M. M. Neris, Yue Fu, Yunlong Zhao, Benjamin Krohn-Hansen, Peng Liu, Yang Yang
Summary: This study describes a metalloredox biocatalysis strategy to repurpose natural cytochromes P450 for catalysing asymmetric radical cyclization to arenes through an unnatural electron transfer mechanism. Directed evolution yielded a series of engineered P450 aromatic radical cyclases with complementary selectivities. The excellent tunability of this metalloenzyme family provides an exciting platform for utilizing free radical intermediates in asymmetric catalysis.
Article
Chemistry, Physical
Amit Kumar Simlandy, Warabhorn Rodphon, Turki M. Alturaifi, Binh Khanh Mai, Hui-Qi Ni, John A. Gurak, Peng Liu, Keary M. Engle
Summary: We report a redox-neutral catalytic coupling of nitroalkanes and unactivated alkenes that proceeds by a directed carbopalladation mechanism. The reaction is enabled by the combination of PdI2 as the precatalyst and HFIP solvent. Complex nitroalkane products, including nitro-containing carbo- and heterocycles, can be prepared under convenient conditions without the need for toxic or corrosive reagents.
