Article
Chemistry, Multidisciplinary
Gefei Li, Yanlong Luo, Juan Mo, Masato Noguchi, Jie Jing, Zhenyang Luo, Shin-ichiro Shoda, Xin-Shan Ye
Summary: A hydrogen bond-assisted alpha-selective glycosylation reaction using DBT B-glycosyl donors was developed for constructing 1,2-cis -alpha-glycosidic bond efficiently in natural products. This method was successfully applied to directly synthesize complex oligosaccharide-derived glycolipids with simple protecting chemistry. Mechanistic studies using NMR spectroscopy and DFT calculation supported the concept of hydrogen bond-assisted glycosylation reaction for alpha-specific construction of O-glycosidic linkage.
CHINESE CHEMICAL LETTERS
(2023)
Article
Chemistry, Organic
Jianpeng Chen, Yu Tang, Biao Yu
Summary: A mild glycosylation method using glycosyl 1-methylimidazole-2-carboxylates has been developed, with the reaction being promoted by metal triflates and triflimides, especially Cu(OTf)(2). The reaction is initiated by coordination of the glycosyl ester donor with the metal cation assisted by the adjacent 1-methylimidazole chelating group.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Review
Chemistry, Multidisciplinary
Akihiro Ishiwata, Katsunori Tanaka, Jiaming Ao, Feiqing Ding, Yukishige Ito
Summary: 1,2-cis-O-glycosylation is essential in the assembly of bioactive glycans with various functions. However, controlling the stereoselectivity of glycosylation and specifically forming 1,2-cis glycosides is challenging. Recent advances in glycosyl donor modification, reaction conditions, and activation methods have been made in the development of 1,2-cis selective glycosylations.
FRONTIERS IN CHEMISTRY
(2022)
Article
Chemistry, Organic
Penghua Li, Hanyingzi Fan, Qiang Tan, Guozhi Xiao
Summary: Highly stereoselective construction of 1,2-cis-Arap linkages has been achieved with a broad range of alcoholic acceptors, including strong nucleophiles and complex bioactive molecules. This method was applied to a regioselective and orthogonal one-pot synthesis of a pentasaccharide, which serves as the structural motif of a side chain in type II arabinogalactan.
Article
Chemistry, Multidisciplinary
Hengfu Xu, Richard N. Schaugaard, Jiayi Li, H. Bernhard Schlegel, Hien M. Nguyen
Summary: This study reports a new stereoselective method for the formation of the 1,2-cis furanosidic linkage using phenanthroline catalysts. The method operates under mild conditions and provides good yields and high selectivities for biologically relevant oligosaccharides and polysaccharides. NMR experiments and density functional theory calculations support an associative mechanism, and the reaction is applicable to various furanosyl bromide donors.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Dancan K. Njeri, Erik Alvarez Valenzuela, Justin R. Ragains
Summary: By substituting the benzyl groups of glucosyl imidate donors with trifluoromethyl, a substantial increase in 1,2-cis-selectivity can be achieved when activated with TMS-I in the presence of triphenylphosphine oxide. The stereoselectivity depends on the number of trifluoromethyl groups, leading to high 1,2-cis-selectivity with reactive alcohol acceptors.
Article
Chemistry, Organic
Tiffany Duong, Erik Alvarez Valenzuela, Justin R. Ragains
Summary: In this study, we demonstrate that the reaction between benzylchalcogenoglycosides and benzyne in the presence of alcohols can proceed highly 1,2-cis-selective O-glycosylation in a solvent-dependent manner. Thioglycosides, selenoglycosides, and alcohols with different nucleophilicities can participate in the reaction, and the need for unusual protecting groups, auxiliary groups, and additives is eliminated.
Article
Chemistry, Multidisciplinary
Xu Ma, Zhitong Zheng, Yue Fu, Xijun Zhu, Peng Liu, Liming Zhang
Summary: This study introduces a strategy for the formation of 1,2-cis-glycosidic linkage using gold catalysis, achieving excellent yields and outstanding selectivities under mild conditions. This strategy is also successfully applied to the synthesis of oligosaccharides.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Biochemistry & Molecular Biology
Levente Homolya, Laszlo Juhasz, Laszlo Somsak
Summary: The study focused on the addition of bromine and chlorine to O-peracylated glycals, resulting in mainly 2,3-trans-diaxial (3-bromo-3-deoxy-alpha-D-heptopyranosylbromide)onic acid derivatives. Despite successful glycosylation reactions, most attempted nucleophilic substitution and elimination reactions only yielded the parent glycal.
CARBOHYDRATE RESEARCH
(2021)
Article
Chemistry, Organic
Polina I. Abronina, Nelly N. Malysheva, Alexander I. Zinin, Natalya G. Kolotyrkina, Leonid O. Kononov
Summary: Glycosylation using different glucosyl donors can lead to different selectivity, with the position of the benzoyl group playing a key role in the alpha selectivity.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Dancan K. Njeri, Justin R. Ragains
Summary: The assigned tetrasaccharide repeating subunit from the Acinetobacter baumannii KL4-associated capsular polysaccharide has been successfully synthesized through chemical synthetic efforts. A convergent synthetic strategy based on a 1,2-cis-selective [2+2] glycosylation was crucial for the synthesis of the fully protected tetrasaccharide.
Article
Chemistry, Organic
Taeok Kim, Michael R. Bell, V. Narasimharao Thota, Todd L. Lowary
Summary: This study reports a one-pot strategy for functionalizing pyranoside 1,2-cis-diols with two different ester protecting groups. The approach selectively acylates through orthoester hydrolysis promoted by a carboxylic acid, and after removal of water and introduction of a coupling agent, the carboxylic acid is esterified with the liberated hydroxyl group. Although applied to 1,2-cis-diols on pyranoside scaffolds, this method can be applicable to similar motifs on any six-membered ring.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Review
Biochemistry & Molecular Biology
Akihiro Ishiwata, Katsunori Tanaka, Yukishige Ito, Hui Cai, Feiqing Ding
Summary: Controlling the stereoselectivity of 1,2-cis glycosylation is a challenging task in glycans synthesis. Various regioisomeric linkages have been identified, and strategies using inter- and intra-molecular methodologies have been explored. Recent advances in Zn salt-mediated cis glycosylation and its applications in alpha-glucans construction are summarized in this review.
Article
Chemistry, Multidisciplinary
Luka Fotovic, Nikola Bedekovic, Vladimir Stilinovic
Summary: A database survey and structural study reveal that protonation and N-methylation increase the probability of halogen atoms participating in halogen bonds in halogenopyridinium cations, although chloropyridines have a lower probability. Crystal structures show that iodo- and bromopyridinium cations form shorter halogen-bonding contacts, while chloropyridinium cations mostly form longer or fail to form halogen bonds. DFT study indicates an increase in the electrostatic potential of the halogen sigma-hole after protonation and N-methylation, but it is not always the most positive site, allowing for alternate binding sites.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Chemistry, Organic
Jason P. Hibbard, Jessalyn G. Yam, Eyad B. Alsalek, Ana Bahamonde
Summary: A mild sustainable protocol has been developed to couple primary alkyl chlorides and bromides with amides, allowing access to a remarkably orthogonal scope without the need for strongly basic conditions, high temperatures, or organometallic catalysts. K3PO4 is used to facilitate the formation of secondary and tertiary amides, with alkylated amide products obtained in good to excellent yields, showing no substantial limitations based on the steric and electronic properties of the coupling partners.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Ren-Zhe Li, Da-Qi Liu, Dawen Niu
Article
Chemistry, Multidisciplinary
Yingwei Wang, Li-Fan Deng, Xia Zhang, Ze-Dong Mou, Dawen Niu
Summary: A general approach for making unnatural amino acids from cysteine derivatives was reported, utilizing an intramolecular radical substitution process to generate alkyl radicals. The generated alkyl radicals participated in diverse C-C bond forming events under mild, photocatalytic conditions at room temperature, and could be performed open to air. The utility of these transformations was further demonstrated in the straightforward synthesis of various previously inaccessible unnatural amino acids and peptides.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Weidong Shang, Sheng-Nan Su, Rong Shi, Ze-Dong Mou, Guo-Qiang Yu, Xia Zhang, Dawen Niu
Summary: Glycosyl sulfoxides appended with an aryl iodide moiety are reported as stable precursors to glycosyl radicals, which can be converted rapidly and efficiently through intramolecular radical substitution for the synthesis of complex C-linked glycoconjugates under mild conditions, including glycopeptidomimetics and carbohydrate-DNA conjugates in aqueous media.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Li-Qiang Wan, Jin-Ge Cao, Dawen Niu, Xia Zhang
Summary: A general and mild approach for preparing alpha-branched aliphatic amines from imines is reported here. This method utilizes a cobalt-catalyzed umpolung alkylation of imines, employs easily available reaction partners, and demonstrates a broad substrate scope. Mechanistic studies suggest a radical pathway for this transformation.
Article
Chemistry, Multidisciplinary
Demeng Xie, Yingwei Wang, Xia Zhang, Zhengyan Fu, Dawen Niu
Summary: This research presents the use of alkyl sulfoxides as precursors to radicals in the synthesis of pyridine derivatives. It demonstrates that alkyl sulfoxides, N-methoxy pyridinium salts, and fluoride anions form electron donor-acceptor complexes in solution, which can undergo a radical chain process upon visible light irradiation to produce various pyridine derivatives efficiently. The broad scope of this reaction extends to different sulfoxides and N-methoxy pyridiniums. The synthetic versatility of sulfoxides as radical precursors adds to their significance as a useful tool in chemistry.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Han-Li Sun, Bin Wu, Da-Qi Liu, Zi-Di Yu, Jun-Jie Wang, Qianyi Liu, Xingchen Liu, Dawen Niu, Jin-Hu Dou, Rong Zhu
Summary: Here, we report the unexpected discovery of a Cu-catalyzed condensation polymerization reaction that converts simple C3 building blocks into polydiynes with C6 repeating units. This reaction utilized a simple system composed of a copper acetylide initiator and an electron-rich phosphine ligand to produce alkyne polymers with high yields, regioselectivity, and functional group compatibility. Hydrogenation of the resulting product yielded a new polyolefin-type backbone, while base-mediated isomerization led to a novel dienyne-based electron-deficient conjugated polymer. Mechanistic studies revealed an alpha-alpha selective Cu-catalyzed dimerization pathway of the C3 unit, followed by organocopper-mediated chain-growth propagation.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
Xiang Pu, Qiu-Di Dang, Lei Yang, Xia Zhang, Dawen Niu
Summary: The authors report a doubly-stereoconvergent, Cu/Mg-catalyzed asymmetric propargylic substitution reaction that can selectively construct products with vicinal congested stereocenters. This reaction uses readily available starting materials, environmentally friendly catalysts, and has a broad substrate scope.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Qian Zhang, Wei Zhang, Ruoyan Cui, Yang Zhang, Dawen Niu
Summary: Here, we present the use of pyrimidinyl sulfones as electrophiles in Ni-catalyzed Suzuki-Miyaura cross-coupling reactions. This method enables the convenient synthesis of pharmaceutically relevant 2,4-disubstituted pyrimidines. The reactions proceed under mild conditions and exhibit a wide range of substrates. The efficient and regioselective cleavage of the C-sulfone bond is observed. Preliminary mechanistic studies suggest the crucial role of the alpha-nitrogen atom in pyrimidine in facilitating these transformations.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Multidisciplinary
Shiyang Xu, Wei Zhang, Caiyi Li, Yanjing Li, Hongxin Zeng, Yingwei Wang, Yang Zhang, Dawen Niu
Summary: We present a method for generating glycosyl radicals under highly acidic conditions. This method utilizes glycosyl sulfinates as radical precursors, which are stable solids and can be easily prepared from commercial starting materials. The method allows for direct installation of glycosyl units onto pyridine rings through the Minisci reaction. We showcase the utility of the method in the late-stage modification of complex drug molecules, including camptothecin. Experimental studies provide insight into the reaction mechanism.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Hongxin Zeng, Yanjing Li, Rongfeng Wu, Daqi Liu, Yang Zhang, Shiyang Xu, Dawen Niu
Summary: Here, a method for synthesizing carbohydrate-DNA conjugates by radical addition is reported. This method utilizes readily available, bench-stable, and unprotected glycosyl sulfinates as precursors to glycosyl radicals. The reaction, which is redox neutral, proceeds under mild and simple conditions and allows for a broad substrate scope. A small library of carbohydrate-DNA conjugates was successfully prepared.
Review
Chemistry, Multidisciplinary
Weidong Shang, Dawen Niu
Summary: The study of carbohydrates has become important in various fields due to their pivotal roles in cellular processes. Chemical glycosylation reactions are highly needed to explore their biological functions. Recent advances in radical pathway glycosylation have shown great potential in developing novel methods for glycoside synthesis.
ACCOUNTS OF CHEMICAL RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Hao Zuo, Chen Zhang, Yang Zhang, Dawen Niu
Summary: A simple and general method for fully unprotected, stereoselective glycosylation of carboxylic acids was developed using bench-stable allyl glycosyl sulfones as donors. The reaction, conducted under basic conditions, showed high efficiencies and selectivities. Both the donor activation stage and the glycosidic bond forming stage were compatible with free hydroxyl groups.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Qingyi Zhao, Yandan Bao, Dawen Niu, Xuan Wang, Xiaojie Lu
Summary: In this study, we discovered two different S-glycosyl transformations in a DNA-encoded library (DEL)-compatible environment. One approach involves 2-chloro-1,3-dimethylimidazolidinium chloride (DMC)-mediated S-glycosylation, but it has limited substrate scope for DEL construction. We also investigated a photoinduced DNA-compatible S-glycosyl transformation using allyl sugar sulfones, which showed excellent compatibility with functional groups and yielded desired DNA-linked glycosyl derivatives. This pioneering DNA-compatible S-glycosyl transformation is a valuable tool for preparing glycosyl DELs and exploring sugar-incorporated delivery systems.
Article
Chemistry, Multidisciplinary
Liang Gong, Qian Zhang, Demeng Xie, Wei Zhang, Shi-Yang Xu, Xia Zhang, Dawen Niu
Summary: A Ni-catalyzed Negishi coupling reaction can prepare 1,2-dialkyl enol ethers in a stereoconvergent fashion, using alpha-oxy-vinylsulfones as electrophiles. This reaction shows unique selectivity and general applicability, indicating potential for further use in cross-coupling reactions.
CHEMICAL COMMUNICATIONS
(2021)