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Heterocyclic chemistry

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https://www.readbyqxmd.com/read/28813151/the-medicinal-and-biological-chemistry-mbc-library-an-efficient-source-on-new-hits
#1
Víctor Sebastián Pérez, Carlos Roca, Mahendra Awale, Jean-Louis Reymond, Ana Martínez, Carmen Gil, Nuria E Campillo
Identification of new hits is one of the biggest challenges in drug discovery. Creating a library of well-characterized drug-like compounds is a key step in this process. Our group has developed an in-house chemical library called Medicinal and Biological Chemistry (MBC) library. This collection has been successfully used to start several medicinal chemistry programs and developed in an accumulation of more than thirty years of experience in drug design and discovery of new drugs for unmet diseases. It contains over 1,000 compounds, mainly heterocyclic scaffolds...
August 16, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28801135/pyrrolo-2-1-f-1-2-4-triazines-from-c-nucleosides-to-kinases-and-back-again-the-remarkable-journey-of-a-versatile-nitrogen-heterocycle
#2
REVIEW
Gregory R Ott, David A Favor
Pyrrolo[2,1-f][1,2,4]triazine, a unique NN bond-containing heterocycle with a bridgehead nitrogen, was first synthesized in the late 1970s but did not find utility until more than a decade later in the early 1990s when it was incorporated into C-nucleosides as a novel purine-like mimetic. This heterocycle remained at the fringes of medicinal chemistry until a confluence of events spurred by the explosion of the kinase inhibitor field in the early 2000s and the pressing need for novel, druggable scaffolds to occupy that exciting space led to numerous applications against diverse therapeutic targets...
July 30, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28796395/indole-and-pyrrole-bx-bench-stable-hypervalent-iodine-reagents-for-heterocycle-umpolung
#3
Paola Caramenti, Stefano Nicolai, Jerome Waser
The one-step synthesis of the bench-stable hypervalent iodine reagents IndoleBX and PyrroleBX using mild Lewis acid catalyzed conditions is reported. The new reagents are stable up to 150 °C and were applied in the C-H arylation of unactivated arenes using either rhodium or ruthenium catalysts. A broad range of heterocyclic systems of high interest for synthetic and medicinal chemistry was accessed in high yields. The developed C-H functionalization could not be achieved using reported reagents or methods, highlighting the unique reactivity of Indole- and Pyrrole-BX...
August 10, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28782779/nucleophile-dependent-formation-of-6-and-7-membered-n-heterocycles-by-platinum-catalysed-cyclisation-of-1-5-bisallenes
#4
María Teresa Quirós, César Hurtado-Rodrigo, María Paz Muñoz
An unprecedented Pt-catalysed cyclisation of N-tethered 1,5-bisallenes in the presence of oxygen nucleophiles is reported, where formation of 6- or 7-membered rings is driven by the choice of nucleophile and the mechanism dictated by the nucleophile and the electronic properties of the bisallene. The reaction in the presence of alcohols gives preferentially vinyltetrahydropyridines with an extra alkoxy group and Pt-H as the active species in the catalytic cycle, while formation of di- and tetrahydroazepines with an extra hydroxyl group is favoured when water is used as nucleophile, via nucleophilic attack/carbocyclization as the favoured pathway...
August 16, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28777537/pushing-chemical-boundaries-with-n-heterocyclic-olefins-nhos-from-catalysis-to-main-group-element-chemistry
#5
Matthew M D Roy, Eric Rivard
N-Heterocyclic olefins (NHOs) have gone from the topic of a few scattered (but important) reports in the early 1990s to very recently being a ligand/reagent of choice in the far-reaching research fields of organocatalysis, olefin and heterocycle polymerization, and low oxidation state main group element chemistry. NHOs are formally derived by appending an alkylidene (CR2) unit onto an N-heterocyclic carbene (NHC), and their pronounced ylidic character leads to high nucleophilicity and soft Lewis basic character at the ligating carbon atom...
August 4, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28776512/copper-ii-bromide-nitrate-and-perchlorate-complexes-with-sterically-demanding-n-6-methylpyridin-2-yl-acetamide-ligands
#6
Anton I Smolentsev
Functionalized acid amides are widely used in biology, medicine, environmental chemistry and many other areas. Among them, pyridine-substituted amides, in particular N-(pyridin-2-yl)acetamide and its derivatives, play an important role due to their excellent chelating properties. The donor properties of these ligands can be effectively modified by introducing electron-donating substituents (e.g. alkyl groups) into the heterocycle. On the other hand, substituents in the α-position of the pyridine ring can create steric hindrance, which significantly influences the coordination number and geometry...
August 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
https://www.readbyqxmd.com/read/28762997/investigating-the-biosynthesis-of-natural-products-from-marine-proteobacteria-a-survey-of-molecules-and-strategies
#7
REVIEW
Marshall L Timmermans, Yagya P Paudel, Avena C Ross
The phylum proteobacteria contains a wide array of Gram-negative marine bacteria. With recent advances in genomic sequencing, genome analysis, and analytical chemistry techniques, a whole host of information is being revealed about the primary and secondary metabolism of marine proteobacteria. This has led to the discovery of a growing number of medically relevant natural products, including novel leads for the treatment of multidrug-resistant Staphylococcus aureus (MRSA) and cancer. Of equal interest, marine proteobacteria produce natural products whose structure and biosynthetic mechanisms differ from those of their terrestrial and actinobacterial counterparts...
August 1, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28759875/an-overview-of-benzo-b-thiophene-based-medicinal-chemistry
#8
Rangappa S Keri, Karam Chand, Srinivasa Budagumpi, Sasidhar Balappa Somappa, Siddappa A Patil, Bhari Mallanna Nagaraja
Among sulfur containing heterocycles, benzothiophene and its derivatives are at the focus as these candidates have structural similarities with active compounds to develop new potent lead molecules in drug design. Benzo[b]thiophene scaffold is one of the privileged structures in drug discovery as this core exhibits various biological activities allowing them to act as anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant, anti-tubercular, anti-diabetic, anti-convulsant agents and many more. Further, numerous benzothiophene-based compounds as clinical drugs have been extensively used to treat various types of diseases with high therapeutic potency, which has led to their extensive developments...
July 22, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28759220/n-heterocyclic-carbene-stabilized-boranthrene-as-a-metal-free-platform-for-the-activation-of-small-molecules
#9
Jordan W Taylor, Alex McSkimming, Camilo F Guzman, W Hill Harman
The multielectron reduction of small molecules (e.g., CO2) is a key aspect of fuel synthesis from renewable electricity. Transition metals have been researched extensively in this role due to their intrinsic redox properties and reactivity, but more recently, strategies that forego transition metal ions for p-block elements have emerged. In this vein, we report an analogue of boranthrene (9,10-diboraanthracene) stabilized by N-heterocyclic carbenes and its one- and two-electron oxidized congeners. This platform exhibits reversible, two-electron redox chemistry at mild potentials and reacts with O2, CO2, and ethylene via formal [4+2] cycloaddition to the central diborabutadiene core...
August 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28751747/synergistic-blending-of-high-valued-heterocycles-inhibits-growth-of-plasmodium-falciparum-in-culture-and-p-berghei-infection-in-mouse-model
#10
Prashant Kumar, Angela O Achieng, Vinoth Rajendran, Prahlad C Ghosh, Brajendra K Singh, Manmeet Rawat, Douglas J Perkins, Prakasha Kempaiah, Brijesh Rathi
A series of phthalimide analogues, novelized with high-valued bioactive scaffolds was synthesized by means of click-chemistry under non-conventional microwave heating and evaluated as noteworthy growth inhibitors of Plasmodium falciparum (3D7 and W2) in culture. Analogues 6a, 6h and 6 u showed highest activity to inhibit the growth of the parasite with IC50 values in submicromolar range. Structure-activity correlation indicated the necessity of unsubstituted triazoles and leucine linker to obtain maximal growth inhibition of the parasite...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28750806/new-methods-for-the-synthesis-of-cannabidiol-derivatives
#11
Ana Lago-Fernandez, Vanessa Redondo, Laura Hernandez-Folgado, Laura Figuerola-Asencio, Nadine Jagerovic
Cannabidiol (CBD) is one of the most abundant components isolated from Cannabis sativa. However, CBD is a nonpsychotropic phytocannabinoid. In the last decade, there has been a growing interest in its therapeutic effects. This is why this natural product represents a lead structure for the development of new cannabinoid compounds. Even though chemistry of CBD has been explored for more than 30 years, the synthesis of only a few derivatives has been described. This chapter first reviews the synthetic methods for the preparation of CBD and derivatives...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28749425/recent-developments-in-the-medicinal-applications-of-silver-nhc-complexes-and-imidazolium-salts
#12
REVIEW
Nicholas A Johnson, Marie R Southerland, Wiley J Youngs
Because of their great structural diversity and multitude of chemical properties, N-heterocyclic carbenes (NHCs) have been utilized in a variety of capacities. Most recently, NHCs have been utilized as carrier molecules for many transition metals in medicinal chemistry. Specifically, Ag(I)-NHCs have been investigated as potent antibacterial agents and chemotherapeutics and have shown great efficacy in both in vitro and in vivo studies. Ag(I)-NHC compounds have been shown to be effective against a wide range of both Gram-positive and Gram-negative bacterial strains...
July 27, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28745875/ruthenium-catalyzed-site-selective-intramolecular-silylation-of-primary-c-h-bonds-for-synthesis-of-sila-heterocycles
#13
Huaquan Fang, Wenjun Hou, Guixia Liu, Zheng Huang
Incorporating the silicon element into bioactive organic molecules has received increasing attention in medicinal chemistry. Moreover, organosilanes are valuable synthetic intermediates for fine chemicals and materials. Transition metal-catalyzed C-H silylation has become an important strategy for C-Si bond formations. However, despite the great advances in aromatic C(sp(2))-H bond silylations, catalytic methods for aliphatic C(sp(3))-H bond silylations are relatively rare. Here we report a pincer ruthenium catalyst for intramolecular silylations of various primary C(sp(3))-H bonds adjacent to heteroatoms (O, N, Si, Ge), including the first intramolecular silylations of C-H bonds α to O, N, and Ge...
August 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28745209/thiazole-containing-heterocycles-with-antimalarial-activity
#14
Mukesh Kumar Kumawat
BACKGROUND: Heterocyclic compounds are the main class of medicinally important compounds. Many heterocyclic compounds bearing a five member ring in their structure have a good spectrum of biological activities. Thiazole is an important class of five membered heterocyclic compounds. Thiazole and its derivatives exhibited a broad range of biological activities due to the presence of various reaction posses. Thiazole, heterocyclic nucleus is present in several potent pharmacologically active molecules such as Sulfathiazole (antimicrobial drug), Ritonavir (antiretroviral drug), Tiazofurin (antineoplastic drug) and Abafungin (antifungal drug) etc...
July 25, 2017: Current Drug Discovery Technologies
https://www.readbyqxmd.com/read/28745208/thiazole-containing-heterocycles-with-cns-activity
#15
Priyanka Kalal, Divyani Gandhi, Prakash Prajapat, Shikha Agarwal
BACKGROUND: Thiazoles are promising scaffolds in the area of medicinal and pharmaceutical chemistry and have accounted to show different pharmacophoric properties. For the last years, thiazole derivatives have focused too much attention to develop different new CNS active agents. It has been broadly used to generate diverse therapeutic agents against various CNS targets. Histamine H3 receptors are seriously involved in the pathophysiology of numerous disorders of the central nervous system...
July 24, 2017: Current Drug Discovery Technologies
https://www.readbyqxmd.com/read/28744934/buttressing-effect-as-key-design-principle-towards-highly-efficient-palladium-n-heterocyclic-carbene-buchwald-hartwig-amination-catalysts
#16
Yin Zhang, Guy Lavigne, Noël Lugan, Vincent César
A thorough structure/activity study aiming at rationalizing the beneficial effect of the substitution of the 4 and 5 positions of the standard 1,3-bis(2,6-diisopropylphenyl)-2H-imidazol-2-ylidene (IPr) ligand has on the catalytic activity of the corresponding Pd-PEPPSI pre-catalysts in N-arylation reaction is described. In addition to the previously reported IPrNMe2 and IPr(NMe2)2 ligands, the new IPrNiPr2 and IPr(NMe2,Cl) ligands bearing, respectively, one bulkier diisopropylamino group and a combination of dimethylamino and chloro substituents have been designed and included in the study...
July 25, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28739962/chemoselective-lewis-pair-polymerization-of-renewable-multivinyl-functionalized-%C3%AE-butyrolactones
#17
Ravikumar R Gowda, Eugene Y-X Chen
Multivinyl-functionalized γ-butyrolactones, γ-vinyl-γ-methyl-α-methylene-γ-butyrolactone (γVMMBL) and γ-allyl-γ-methyl-α-methylene-γ-butyrolactone (γAMMBL), have been synthesized from biorenewable ethyl levulinate and effectively polymerized by Lewis pairs consisting of an organic N-heterocyclic carbene Lewis base and a strong organo-Lewis acid E(C6F5)3 (E = Al, B). This Lewis pair polymerization is quantitatively chemoselective, proceeds exclusively via polyaddition across the conjugated α-methylene double bond without participation of the γ-vinyl or γ-allyl double bond, and produces high-molecular-weight functionalized polymers with unimodal molecular-weight distributions...
August 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28731275/exceptionally-strong-electron-donating-ability-of-bora-ylide-substituent-vis-%C3%A3-vis-silylene-and-silylium-ion
#18
Alfredo Rosas-Sánchez, Isabel Alvarado-Beltran, Antoine Baceiredo, Nathalie Saffon-Merceron, Stéphane Massou, Vicenç Branchadell, Tsuyoshi Kato
Electropositive boron-based substituent (phosphonium bora-ylide) with an exceptionally strong π- and σ-electron donating character dramatically increases the stability of a new type of N-heterocyclic silylene 2 featuring amino- and bora-ylide-substituents. Moreover, the related silylium ion 4 and transition-metal-silylene complexes, with trigonal-planar geometries around the silicon center, are also well stabilized. Therefore, the N,B-heterocyclic silylene 2 can be used as a strongly electron-donating innocent ligand in coordination chemistry similarly to N-heterocyclic carbenes...
July 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28723098/a-new-area-in-main-group-chemistry-zerovalent-monoatomic-silicon-compounds-and-their-analogues
#19
Shenglai Yao, Yun Xiong, Matthias Driess
Monoatomic zerovalent main-group element complexes emerged very recently and attracted increasing attention of both theoretical and experimental chemists. In particular, zerovalent silicon complexes and their congeners (metallylones) stabilized by neutral Lewis donors are of significant importance not only because of their intriguing electronic structure but also because they can serve as useful building blocks for novel chemical species. Featuring four valence electrons as two lone pairs at the central atoms, such complexes may form donor-acceptor adducts with Lewis acids...
July 19, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28718642/predictive-model-for-site-selective-aryl-and-heteroaryl-c-h-functionalization-via-organic-photoredox-catalysis
#20
Kaila A Margrey, Joshua B McManus, Simone Bonazzi, Frederic Zecri, David A Nicewicz
Direct C-H functionalization of aromatic compounds is a useful synthetic strategy that has garnered much attention because of its application to pharmaceuticals, agrochemicals, and late-stage functionalization reactions on complex molecules. On the basis of previous methods disclosed by our lab, we sought to develop a predictive model for site selectivity and extend this aryl functionalization chemistry to a selected set of heteroaromatic systems commonly used in the pharmaceutical industry. Using electron density calculations, we were able to predict the site selectivity of direct C-H functionalization in a number of heterocycles and identify general trends observed across heterocycle classes...
August 16, 2017: Journal of the American Chemical Society
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