4687-25-6Relevant articles and documents
Benzofurans as efficient dienophiles in normal electron demand [4 + 2] cycloadditions
Chopin, Nathalie,Gerard, Helene,Chataigner, Isabelle,Piettre, Serge R.
, p. 1237 - 1246 (2009)
Dearomatization of electron-poor benzofurans is possible through involvement of the aromatic 2,3-carbon-carbon double bond as dienophile in normal electron demand [4 + 2] cycloadditions. The tricyclic heterocycles thereby produced bear a quaternary center at the cis ring junction, a feature of many alkaloids such as morphine, galanthamine, or lunaridine. The products arising from the reaction have been shown to depend on different factors among which the type of the electron-withdrawing substituent of the benzofuran, the nature of the reacting diene, and the method of activation. In the presence of all-carbon dienes, the reaction yields the expected Diels-Alder adducts. When thermal activation is insufficient, a biactivation associating zinc chloride catalysis and high pressure is required to generate the cycloadducts in good yields and high stereoselectivities, for instance, when cyclohexadiene is involved in the process. The use of more functionalized dienes, such as those bearing alkoxy or silyloxy substituents, also shows the limits of the thermal activation, and hyperbaric conditions are, in this case, well-suited. The involvement of Danishefsky's diene induces a competition in the site of reactivity. The aromatic 2,3-carbon-carbon double bond is unambiguously the most reactive dienophile, and the 3-carbonyl unit becomes a competitive site of reactivity with benzofurans bearing substituents prone to heterocyloaddition, in particular under Lewis acid activation. The sequential involvment of both the aromatic double bond and the carbonyl moiety as dienophiles is then possible by using an excess of diene under high-pressure activation. In line with the experimental results, DFT computations suggest that the Diels-Alder process involving the aromatic double bond is preferred over the hetero-Diels-Alder route through an asynchronous concerted transition state. However, Lewis acid catalysis appears to favor the heterocycloaddition pathway through a stepwise mechanism in some cases. 2009 American Chemical Society.
Microwave assisted synthesis of novel functionalized hydantoin derivatives and their conversion to 5-(Z) arylidene-4H-imidazoles
Kamila, Sukanta,Ankati, Haribabu,Biehl, Edward R.
, p. 5527 - 5537 (2011)
2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a-n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol- 5(4H)-ones 3a-c with suitably substituted secondary amines. The starting 2-thioxoimidazo
Direct C-2 Carboxylation of 3-Substituted Indoles Using a Combined Br?nsted Base Consisting of LiO-tBu/CsF/18-crown-6
Shigeno, Masanori,Tohara, Itsuki,Nozawa-Kumada, Kanako,Kondo, Yoshinori
supporting information, p. 1987 - 1991 (2020/04/09)
Herein, we report that a combination of LiO-tBu, CsF, and 18-crown-6 can be used to carry out the carboxylation of indole derivatives at the C-2 position under an ambient CO2 atmosphere. Substrates bearing an electrophilic substituent (i.e., cyano, formyl, benzoyl, phenylsulfonyl, phenylsulfinyl, and chloride) at the C-3 position are smoothly converted into their corresponding carboxylated products with high functional group compatibility.
Visible-Light-Induced Radical Carbo-Cyclization/ gem-Diborylation through Triplet Energy Transfer between a Gold Catalyst and Aryl Iodides
Hashmi, A. Stephen K.,Rominger, Frank,Si, Xiaojia,Zhang, Lumin
, p. 10485 - 10493 (2020/07/03)
Geminal diboronates have attracted significant attention because of their unique structures and reactivity. However, benzofuran-, indole-, and benzothiophene-based benzylic gem-diboronates, building blocks for biologically relevant compounds, are unknown. A promising protocol using visible light and aryl iodides for constructing valuable building blocks, including benzofuran-, indole-, and benzothiophene-based benzylic gem-diboronates, via radical carbo-cyclization/gem-diborylation of alkynes with a high functional group tolerance is presented. The utility of these gem-diboronates has been demonstrated by a 10 g scale conversion, by versatile transformations, by including the synthesis of approved drug scaffolds and two approved drugs, and even by polymer synthesis. The mechanistic investigation indicates that the merging of the dinuclear gold catalyst (photoexcitation by 315-400 nm UVA light) with Na2CO3 is directly responsible for photosensitization of aryl iodides (photoexcitation by 254 nm UV light) with blue LED light (410-490 nm, λmax = 465 nm) through an energy transfer (EnT) process, followed by homolytic cleavage of the C-I bond in the aryl iodide substrates.
Mercapto-amide boronic acid derivative and application thereof as MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase) inhibitor
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, (2019/09/14)
The invention provides a compound of a formula (I) shown in the specification, or a conformational isomer, or an optical isomer or a pharmaceutically acceptable salt thereof. The compound of the formula (I) shown in the specification has excellent broad-spectrum inhibitory activity on MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase), and can be used for preparing MBL and/or SBL inhibitors. Moreover, the compound disclosed by the invention has excellent antibacterial activity on multiple drug-resistant bacteria and is capable of reversing drug resistance of carbapenem drug-resistant bacteria, and the antibacterial effect of the compound is prior to those of positive control products such as L-captopril and tazobactam. The compound disclosed by the invention has very great potential in preparation of MBL/SBL dual inhibitors and medicines reversing drug resistance of carbapenem drug-resistance bacteria.
Structure-based development of (1-(3′-Mercaptopropanamido)methyl)boronic Acid Derived Broad-Spectrum, Dual-Action Inhibitors of Metallo- And Serine-β-lactamases
Wang, Yao-Ling,Liu, Sha,Yu, Zhu-Jun,Lei, Yuan,Huang, Meng-Yi,Yan, Yu-Hang,Ma, Qiang,Zheng, Yang,Deng, Hui,Sun, Ying,Wu, Chengyong,Yu, Yamei,Chen, Qiang,Wang, Zhenling,Wu, Yong,Li, Guo-Bo
, p. 7160 - 7184 (2019/08/28)
The emergence and spread of bacterial pathogens acquired metallo-β-lactamase (MBL) and serine-β-lactamase (SBL) medicated β-lactam resistance gives rise to an urgent need for the development of new dual-action MBL/SBL inhibitors. Application of a pharmacophore fusion strategy led to the identification of (2′S)-(1-(3′-mercapto-2′-methylpropanamido)methyl)boronic acid (MS01) as a new dual-action inhibitor, which manifests broad-spectrum inhibition to representative MBL/SBL enzymes, including the widespread VIM-2 and KPC-2. Guided by the VIM-2:MS01 and KPC-2:MS01 complex structures, further structural optimization yielded new, more potent dual-action inhibitors. Selectivity studies indicated that the inhibitors had no apparent inhibition to human angiotensin-converting enzyme-2 and showed selectivity across serine hydrolyases in E. coli and human HEK293T cells labeled by the activity-based probe TAMRA-FP. Moreover, the inhibitors displayed potentiation of meropenem efficacy against MBL- or SBL-positive clinical isolates without apparent cytotoxicity. This work will aid efforts to develop new types of clinically useful dual-action inhibitors targeting MBL/SBL enzymes.
Facile One-Pot Transformation of Primary Alcohols into 3-Aryl- and 3-Alkyl-isoxazoles and -pyrazoles
Kobayashi, Eiji,Togo, Hideo
, p. 3723 - 3735 (2019/09/30)
Various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylisoxazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, NH 2 OH, and then NCS, followed by reaction with alkynes in the presence of Et 3 N. Similarly, various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylpyrazoles in good yields in one pot by successive treatment with PhI(OAc) 2 in the presence of TEMPO, PhNHNH 2, and then NCS and decyl methyl sulfide, followed by reaction with alkynes in the presence of Et 3 N. Thus, both 3-aryl- and 3-alkylisoxazoles, and 3-aryl- and 3-alkylpyrazoles could be prepared from readily available primary alcohols in one pot under transition-metal-free conditions.
α-Arylidene Diacylglycerol-Lactones (DAG-Lactones) as Selective Ras Guanine-Releasing Protein 3 (RasGRP3) Ligands
Ann, Jihyae,Czikora, Agnes,Saini, Amandeep S.,Zhou, Xiaoling,Mitchell, Gary A.,Lewin, Nancy E.,Peach, Megan L.,Blumberg, Peter M.,Lee, Jeewoo
supporting information, p. 6261 - 6276 (2018/06/11)
Diacylglycerol-lactones have proven to be a powerful template for the design of potent ligands targeting C1 domains, the recognition motif for the cellular second messenger diacylglycerol. A major objective has been to better understand the structure activity relations distinguishing the seven families of signaling proteins that contain such domains, of which the protein kinase C (PKC) and RasGRP families are of particular interest. Here, we synthesize a series of aryl- and alkyl-substituted diacylglycerol-lactones and probe their relative selectivities for RasGRP3 versus PKC. Compound 96 showed 73-fold selectivity relative to PKCα and 45-fold selectivity relative to PKC? for in vitro binding activity. Likewise, in intact cells, compound 96 induced Ras activation, a downstream response to RasGRP stimulation, with 8-29 fold selectivity relative to PKCδ S299 phosphorylation, a measure of PKCδ stimulation.
Substrate-Tuned Catalysis of the Radical S-Adenosyl- L -Methionine Enzyme NosL Involved in Nosiheptide Biosynthesis
Ji, Xinjian,Li, Yongzhen,Ding, Wei,Zhang, Qi
, p. 9021 - 9024 (2015/08/03)
NosL is a radical S-adenosyl-L-methionine (SAM) enzyme that converts L-Trp to 3-methyl-2-indolic acid, a key intermediate in the biosynthesis of a thiopeptide antibiotic nosiheptide. In this work we investigated NosL catalysis by using a series of Trp analogues as the molecular probes. Using a benzofuran substrate 2-amino-3-(benzofuran-3-yl)propanoic acid (ABPA), we clearly demonstrated that the 5′-deoxyadenosyl (dAdo) radical-mediated hydrogen abstraction in NosL catalysis is not from the indole nitrogen but likely from the amino group of L-Trp. Unexpectedly, the major product of ABPA is a decarboxylated compound, indicating that NosL was transformed to a novel decarboxylase by an unnatural substrate. Furthermore, we showed that, for the first time to our knowledge, the dAdo radical-mediated hydrogen abstraction can occur from an alcohol hydroxy group. Our study demonstrates the intriguing promiscuity of NosL catalysis and highlights the potential of engineering radical SAM enzymes for novel activities.
FLUORESCENCE MODULATORS
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Page/Page column 123, (2012/09/10)
The present invention relates to fluorescence lifetime modulators, conjugates comprising fluorescence lifetime modulators moieties and methods of making them. The present invention further relates to the use of the fluorescence lifetime modulators and conjugates comprising the fluorescence lifetime modulator moieties for measuring the activity and detection of enzymes and for the study of protein-protein and protein-ligand interactions.
