- Iron-Catalyzed Vinylzincation of Terminal Alkynes
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Organozinc reagents are among the most commonly used organometallic reagents in modern synthetic chemistry, and multifunctionalized organozinc reagents can be synthesized from structurally simple, readily available ones by means of alkyne carbozincation. However, this method suffers from poor tolerance for terminal alkynes, and transformation of the newly introduced organic groups is difficult, which limits its applications. Herein, we report a method for vinylzincation of terminal alkynes catalyzed by newly developed iron catalysts bearing 1,10-phenanthroline-imine ligands. This method provides efficient access to novel organozinc reagents with a diverse array of structures and functional groups from readily available vinylzinc reagents and terminal alkynes. The method features excellent functional group tolerance (tolerated functional groups include amino, amide, cyano, ester, hydroxyl, sulfonyl, acetal, phosphono, pyridyl), a good substrate scope (suitable terminal alkynes include aryl, alkenyl, and alkyl acetylenes bearing various functional groups), and high chemoselectivity, regioselectivity, and stereoselectivity. The method could significantly improve the synthetic efficiency of various important bioactive molecules, including vitamin A. Mechanistic studies indicate that the new iron-1,10-phenanthroline-imine catalysts developed in this study have an extremely crowded reaction pocket, which promotes efficient transfer of the vinyl group to the alkynes, disfavors substitution reactions between the zinc reagent and the terminal C–H bond of the alkynes, and prevents the further reactions of the products. Our findings show that iron catalysts can be superior to other metal catalysts in terms of activity, chemoselectivity, regioselectivity, and stereoselectivity when suitable ligands are used.
- Huang, Qiang,Su, Yu-Xuan,Sun, Wei,Hu, Meng-Yang,Wang, Wei-Na,Zhu, Shou-Fei
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p. 515 - 526
(2022/01/08)
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- Visible-Light-Induced [4+2] Annulation of Thiophenes and Alkynes to Construct Benzene Rings
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The [4+2] annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible-light induced [4+2] annulation of thiophenes and alkynes, to afford benzene rings, is presented. Under simple and mild reaction conditions, the ready availability and structural diversity of thiophenes and alkynes permit the facile synthesis of several substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain the high regioselectivity of the reaction.
- Song, Chunlan,Dong, Xin,Wang, Zhongjie,Liu, Kun,Chiang, Chien-Wei,Lei, Aiwen
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supporting information
p. 12206 - 12210
(2019/07/31)
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- Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes
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Gold(i)-catalyzed cross-coupling reactions of aryldiazonium salts with organostannanes are described. This redox neutral strategy offers an efficient approach to diverse biaryls, vinyl arenes and arylacetylenes. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the in situ formation of Ph3PAuIR (R = aryl, vinyl and alkynyl) species which is crucial for the activation of aryldiazonium salts.
- Akram, Manjur O.,Shinde, Popat S.,Chintawar, Chetan C.,Patil, Nitin T.
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supporting information
p. 2865 - 2869
(2018/05/03)
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- An NNN-Pincer-Cobalt Complex Catalyzed Highly Markovnikov-Selective Alkyne Hydrosilylation
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A new NNN pincer (amine-pyridine-imine, API) cobalt complex, which is bench-stable and is applicable for the highly efficient and regioselective hydrosilylation of terminal alkynes, is developed. A broad set of α-vinylsilanes was successfully synthesized in good to high yields with up to 98/2 Markovnikov regioselectivity. This protocol can be readily scaled up for gram-scale synthesis and demonstrates the most efficient cobalt-catalyzed hydrosilylation of alkynes with turnover frequencies as high as 126720 h-1 to date.
- Ibrahim, Jessica Juweriah,Yang, Yong,Zhang, Shaochun
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- Discovery of a novel series of N-hydroxypyridone derivatives protecting astrocytes against hydrogen peroxide-induced toxicity via improved mitochondrial functionality
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Astrocytes play a key role in brain homeostasis, protecting neurons against neurotoxic stimuli such as oxidative stress. Therefore, the neuroprotective therapeutics that enhance astrocytic functionality has been regarded as a promising strategy to reduce brain damage. We previously reported that ciclopirox, a well-known antifungal N-hydroxypyridone compound, protects astrocytes from oxidative stress by enhancing mitochondrial function. Using the N-hydroxypyridone scaffold, we have synthesized a series of cytoprotective derivatives. Mitochondrial activity assay showed that N-hydroxypyridone derivatives with biphenyl group have comparable to better protective effects than ciclopirox in astrocytes exposed to H2O2. N-hydroxypyridone derivatives, especially 11g, inhibited H2O2-induced deterioration of mitochondrial membrane potential and oxygen consumption rate, and significantly improved cell viability of astrocytes. The results indicate that the N-hydroxypyridone motif can provide a novel cytoprotective scaffold for astrocytes via enhancing mitochondrial functionality.
- Singh, Sarbjit,Goo, Ja-Il,Noh, Hyojin,Lee, Sung Jae,Kim, Myoung Woo,Park, Hyejun,Jalani, Hitesh B.,Lee, Kyeong,Kim, Chunsook,Kim, Won-Ki,Ju, Chung,Choi, Yongseok
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p. 1394 - 1405
(2017/02/18)
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- Progress towards water-soluble triazole-based selective MMP-2 inhibitors
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Water solubility is a key aspect that needs to be addressed to obtain drug-like compounds. In an effort to improve the water solubility of our recently reported nanomolar matrix metalloproteinase type 2 (MMP-2) inhibitors based on triazole-substituted hydroxamates, we synthesized a new series of α-sulfone, α-tetrahydropyran and α-piperidine, α-sulfone clicked hydroxamates and determined their inhibitory activities against both MMP-2 and MMP-9. The best results were found for 13e, a water-soluble compound that displays a low nanomolar activity against MMP-2 and is 26-fold less active against MMP-9. This finding allowed us to pursue in vitro permeability through the Caco-2 monolayer and opened the possibility of carrying out further preclinical investigations. Docking and MD simulations have been performed in order to rationalize the biological results. The inhibitory activity of this compound against a panel of ten MMPs was determined showing an interesting MMP-2/MMP-1, -8, and -14 selectivity profile. The cytotoxicity and anti-invasive activity of the compounds on highly metastatic human fibrosarcoma tumor cells (HT1080) were determined, showing, at 10 μM concentration, a decrease in cell invasiveness up to 80%.
- Fabre, Benjamin,Filipiak, Kamila,Zapico, Jose Maria,Diaz, Natalia,Carbajo, Rodrigo J.,Schott, Anne K.,Martinez-Alcazar, Maria Paz,Suarez, Dimas,Pineda-Lucena, Antonio,Ramos, Ana,De Pascual-Teresa, Beatriz
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p. 6623 - 6641
(2013/09/24)
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- Synthesis and structure-activity relationship of histone deacetylase (HDAC) inhibitors with triazole-linked cap group
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Histone deacetylase (HDAC) inhibition is a recent, clinically validated therapeutic strategy for cancer treatment. Small molecule HDAC inhibitors identified so far fall in to three distinct structural motifs: the zinc-binding group (ZBG), a hydrophobic linker, and a recognition cap group. Here we report the suitability of a 1,2,3-triazole ring as a surface recognition cap group-linking moiety in suberoylanilide hydroxamic acid-like (SAHA-like) HDAC inhibitors. Using "click" chemistry (Huisgen cycloaddition reaction), several triazole-linked SAHA-like hydroxamates were synthesized. Structure-activity relationship revealed that the position of the triazole moiety as well as the identity of the cap group markedly affected the in vitro HDAC inhibition and cell growth inhibitory activities of this class of compounds.
- Chen, Po C.,Patil, Vishal,Guerrant, William,Green, Patience,Oyelere, Adegboyega K.
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p. 4839 - 4853
(2008/12/21)
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- Amino-5-(6-membered)heteroarylimidazolone compounds and the use thereof for beta-secretase modulation
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The present invention provides a 2-amino-5-heteroaryl-5-phenylimidazolone compound of formula I The present invention also provides methods for the use thereof to inhibit β-secretase (BACE) and treat β-amyloid deposits and neurofibrillary tangles
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Page/Page column 11
(2008/06/13)
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- Direct diazo-transfer reaction on β-lactam: Synthesis and preliminary biological activities of 6-triazolylpenicillanic acids
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In this study we report the first example of a direct diazo-transfer reaction on readily available 6-aminopenicillanates to give 6-azidopenicillanates in high yield. Subsequent Cu(I)-catalyzed Huisgen cycloaddition between these 6-azidopenicillanates and assorted terminal alkynes facilely furnished 6-triazolylpenicillanic acids. Preliminary biological screening indicates that these triazolylpenicillanic acids possess low to moderate antibacterial activities.
- Chen, Po C.,Wharton, Rebekah E.,Patel, Pratiq A.,Oyelere, Adegboyega K.
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p. 7288 - 7300
(2008/03/28)
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- Arylsulfonamidobenzylic compounds
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Arylsulfonamidobenzyl alcohols, amines and sulfonamides are provided which are useful in treating lipid disorders, metabolic diseases and cell-proliferative diseases.
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