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Heterocyclic chemistry

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https://www.readbyqxmd.com/read/29450929/dehydration-polymerization-for-poly-hetero-arene-conjugated-polymers
#1
Derek Schipper, Rafael Alberto Mirabal, Luke Vanderzwet, Sara Abuadas, Michael Emmett
The lack of scalable and sustainable methods to prepare conjugated polymers belies their importance in many enabling technologies. Accessing high-performance poly(hetero)arene conjugated polymers via dehydration has remained an unsolved problem in synthetic chemistry and has historically required transitional-metal coupling reactions. Here we report a dehydration method that allows access to conjugated heterocyclic materials. Using the technique, we have prepared a series of small molecules and polymers. The reaction avoids using transition metals, proceeds at room temperature, the only required reactant is a simple base and water is the sole by-product...
February 15, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29450652/enhanced-tumor-diagnostic-and-therapeutic-effect-of-mesoporous-silica-nanoparticle-mediated-pre-targeted-strategy
#2
Gaochao Lv, Ke Li, Ling Qiu, Ying Peng, Xueyu Zhao, Xi Li, Qingzhu Liu, Shanshan Wang, Jianguo Lin
PURPOSE: Improving the targeting efficiency of imaging agents or anticancer drugs has become essential in the current primary mission to enhance the diagnostic or therapeutic effects. To improve the tumor diagnosis and therapy effect, a promising drug-delivery and targeting strategy was established based on the bioorthogonal chemistry. METHOD: The delivery system was composed of the pre-targeting carrier Biotin-MSNs-DBCO nanoparticles and the azido cargoes. The fluorescence probe 1-(3-azidopropyl) fluorescein (FITC-N 3 ) and ruthenium N-heterocyclic carbene complex N 3 -S-S-NHC-Ru were synthesized and served as the tumor imaging and therapy probes, respectively...
February 14, 2018: Pharmaceutical Research
https://www.readbyqxmd.com/read/29446188/synergistic-photoredox-and-organocatalysis-for-inverse-hydroboration-of-imines
#3
Jin Xie
The first catalytic inverse hydroboration of imines with N-heterocyclic carbene boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination brings a promising platform to promote NHC-boryl radical chemistry under sustainable and radical initiator free conditions. The highly important functional group compatibility and possible application in late-stage hydroboration represent an important step-forward to an enhanced -amino organoboron lead library.
February 15, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29433143/pyrrolopyrimidine-a-multifaceted-scaffold-in-cancer-targeted-therapy
#4
Mai Adel, Rabah A T Serya, Deena S Lasheen, Khaled A M Abouzid
Pyrrolopyrimidine derivatives represent a class of biologically active heterocyclic compounds which can serve as promising scaffolds that display remarkable biological activities, such as anti-inflammatory, antimicrobial, antiviral and anticancer. In the last few years, several pyrrolopyrimidine derivatives have been approved by the US FDA and in other countries for the treatment of different diseases or are currently in phase I/II clinical trials. Due to their inimitable antioxidant and anti-tumor properties, researchers were inspired to develop novel derivatives for the treatment of different types of cancer...
February 12, 2018: Drug Research
https://www.readbyqxmd.com/read/29407992/new-insights-in-au-nhcs-complexes-as-anticancer-agents
#5
REVIEW
Marina Porchia, Maura Pellei, Marika Marinelli, Francesco Tisato, Fabio Del Bello, Carlo Santini
Within the research field of antitumor metal-based agents alternative to platinum drugs, gold(I/III) coordination complexes have always been in the forefront due mainly to the familiarity of medicinal chemists with gold compounds, whose application in medicine goes back in the ancient times, and to the rich chemistry shown by this metal. In the last decade, N-heterocyclic carbene ligands (NHC), a class of ligands that largely resembles the chemical properties of phosphines, became of interest for gold(I) medicinal applications, and since then, the research on NHC-gold(I/III) coordination complexes as potential antiproliferative agents boosted dramatically...
January 31, 2018: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29384540/s-block-metal-complexes-of-pc-h-p-bridged-chalcogen-centred-methanides-comparisons-with-isoelectronic-pnp-bridged-monoanions
#6
Tristram Chivers, Ramalingam Thirumoorthi
The chemistry of the chalcogen-centred methanides [HC(PR2E)2]- (E = S, Se, Te; R = alkyl, aryl) (PC(H)P-bridged anions) is less well-developed than that of the isoelectronic imidodiphosphinates [N(PR2E)2]-, which are PNP-bridged analogues. The objective of this Perspective is to compare the chemistry of s-block metal complexes of the PC(H)P- and PNP-bridged anions in the context of synthetic approaches, X-ray (solid-state) structures, multinuclear NMR spectra, redox behaviour, and applications in coordination and inorganic heterocyclic chemistry...
January 31, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29383949/recent-developments-on-triazole-nucleus-in-anticonvulsant-compounds-a-review
#7
Ming-Xia Song, Xian-Qing Deng
Epilepsy is one of the common diseases seriously threatening life and health of human. More than 50 million people are suffering from this condition and anticonvulsant agents are the main treatment. However, side effects and intolerance, and a lack of efficacy limit the application of the current anticonvulsant agents. The search for new anticonvulsant agents with higher efficacy and lower toxicity continues to be the focus and task in medicinal chemistry. Numbers of triazole derivatives as clinical drugs or candidates have been frequently employed for the treatment of various types of diseases, which have proved the importance of this heterocyclic nucleus in drug design and discovery...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/29377684/a-general-strategy-for-site-selective-incorporation-of-deuterium-and-tritium-into-pyridines-diazines-and-pharmaceuticals
#8
John Koniarczyk, David Hesk, Alix Overgard, Ian W Davies, Andrew McNally
Methods to incorporate deuterium and tritium atoms into organic molecules are valuable for medicinal chemistry. The prevalence of pyridines and diazines in pharmaceuticals means that new ways to label these heterocycles will present opportunities in drug design and facilitate absorption, distribution, metabolism and excretion (ADME) studies. A broadly applicable protocol is presented wherein pyridines, diazines and pharmaceuticals are converted into heterocyclic phosphonium salts and then isotopically labeled...
January 29, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29376495/anti-inflammatory-anti-allergy-agents-in-medicinal-chemistry-formerly-current-medicinal-chemistry-anti-inflammator
#9
Ashwani Kumar Dhingra, Bhawna Chopra, Jagdeep Singh Dua, Deo N Parsad
The search of novel anti-inflammatory agent is not considered as an ending process, since most of the clinically used anti-inflammatory drugs such as NSAIDs, Coxibs and GCs are allied with considerable toxicity. However, numerous approaches were used to overcome the toxicity level such as co-administration with suitable agent/substance which provides protection against toxicity as well to synthesise new potent and safe anti-inflammatory drug. Although the drug treatment has been improved steadily but yet, it is still a challenge for the medicinal chemists to identify more potent therapeutic agents to treat or reduce the symptoms of inflammatory diseases...
January 26, 2018: Anti-inflammatory & Anti-allergy Agents in Medicinal Chemistry
https://www.readbyqxmd.com/read/29368977/quinazoline-and-quinazolinone-as-important-medicinal-scaffoldes-a-comparative-patent-review-2011-2016
#10
Abdul Hameed, Mariya Al-Rashida, Maliha Uroos, Syed Abid Ali, Arshia, Marium Ishtiaq, Khalid Mohammed Khan
Quinazoline and quinazolinone scaffolds represent an important class of biologically active nitrogen heterocyclic compounds. A variety of marketed drugs are based on these moieties. A diverse range of molecules with quinazoline/quinazolinone moieties have been reported to exhibit broad spectrum of biological activities. Area covered: This review covers recent efforts in the synthesis and biological screening of quinazoline/quinazolinone based compounds from 2011-2016. Expert Opinion: Quinazoline and quinazolinones represent a diverse class of biologically active nitrogen heterocyclic compounds with immense therapeutic potential...
January 25, 2018: Expert Opinion on Therapeutic Patents
https://www.readbyqxmd.com/read/29363830/the-viability-of-c5-protonated-and-c4-c5-ditopic-carbanionic-abnormal-nhcs-a-new-dimension-in-nhc-chemistry
#11
Rajendra Ghadwal, Dennis Rottschäfer, Falk Ebeler, Till Strothmann, Beate Neumann, Hans-Georg Stammler, Andreas Mix
The first C5-protonated abnormal N-heterocyclic carbene (aNHC), PhC{N(2,6-iPr2C6H3)}2CHC: (4) is readily accessible by C4-deprotonation of [ArC{N(2,6-iPr2C6H3)}2CHCH]X (3a-X) (Ar = Ph, X = Br or I) with a base. The aNHC 4 is stable at 298 K in [D8]THF solution and has been spectroscopically characterized. The facile availability of 4 enables the synthesis of a series of main-group compounds as well as transition metal complexes featuring a new phosphorus-aNHC hybrid ligand. Double deprotonation of [ArC{N(2,6-iPr2C6H3)}2CHCH]X (Ar = Ph, 3a-X (X = Br or I); 4-Tol, 3b-Br; 4-DMP, 3c-Br; Tol = MeC6H4, DMP = Me2NC6H4) with nBuLi yields the C4,C5-ditopic carbanionic aNHCs, [ArC{N(2,6-iPr2C6H3)}2(C:)2]Li(THF)n (Ar = Ph, 13a; 4-Tol, 13b; 4-DMP, 13c), which on treatment with Ph2PCl affords cationic vicinal bis-phosphine derivatives [ArC{N(2,6-iPr2C6H3)}2{C(PPh2}2]X (Ar = Ph, 14a-X, X = Br or I; 4-Tol, 14b-Br; 4-DMP, 14c-Br)...
January 24, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29359909/exploration-of-c-h-transformations-of-aldehyde-hydrazones-radical-strategies-and-beyond
#12
Pan Xu, Weipeng Li, Jin Xie, Chengjian Zhu
The chemistry of hydrazones has gained great momentum due to their involvement throughout the evolution of organic synthesis. Herein, we discuss the tremendous developments in both the methodology and application of hydrazones. Hydrazones can be recognized not only as synthetic equivalents to aldehydes and ketones but also as versatile synthetic building blocks. Consequently, they can participate in a range of practical synthetic transformations. Furthermore, hydrazone derivatives display a broad array of biological activities and have been widely applied as pharmaceuticals...
January 23, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29334758/anticancer-thiosemicarbazones-chemical-properties-interaction-with-iron-metabolism-and-resistance-development
#13
Petra Heffeter, Veronika F S Pape, Eva A Enyedy, Bernhard K Keppler, Gergely Szakas, Christian R Kowol
SIGNIFICANCE: During the last decades, thiosemicarbazones have been clinically developed for a variety of diseases including tuberculosis, viral infections, malaria and cancer. With regard to malignant diseases, the class of α-N-heterocyclic thiosemicarbazones, and here especially Triapine, was intensively developed in multiple clinical phase I/II trials. Recent Advances: Very recently two new derivatives, namely COTI-2 and DpC have entered phase I evaluation. Based on the strong metal-chelating/metal-interacting properties of thiosemicarbazones, interference with the cellular iron (and copper) homeostasis is assumed to play an important role in their biological activity...
January 15, 2018: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29328633/size-induced-segregation-in-the-stepwise-microhydration-of-hydantoin-and-its-role-on-proton-induced-charge-transfer
#14
Florent Calvo, Marie-Christine Bacchus-Montabonel
Recent photochemistry experiments provided evidence for the formation of hydantoin by irradiation of interstellar ice analogues. The significance of these results and the importance of hydantoin in prebiotic chemistry and polypeptide synthesis motivate the present theoretical investigation, in which we analyzed the effects of stepwise hydration on the structures, electronic and thermodynamical properties of microhydrated hydantoin using a variety of computational approaches. We generally find microhydration to proceed around the hydantoin heterocycle until 5 water molecules are reached, at which stage hydration becomes segregated with a water cluster forming aside the heterocycle...
January 12, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29315910/early-late-heterobimetallic-tantalum-rhodium-species-assembled-through-a-novel-bifunctional-nhc-oh-ligand
#15
Ravi Srivastava, Raphaël Moneuse, Julien Petit, Paul-Alexis Pavard, Vincent Dardun, Madleen Rivat, Pauline Schiltz, Marius Solari, Erwann Jeanneau, Laurent Veyre, Chloé Thieuleux, Elsje Alessandra Quadrelli, Clement Camp
The straightforward synthesis of a new unsymmetrical hydroxyl-tethered N-heterocyclic carbene (NHC) ligand, HL is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif is used to yield i) the first tantalum complex displaying both a Fischer-type and a Schrock-type carbene ligand and ii) a unique NHC-based early-late heterobimetallic complex. More specifically, protonolysis chemistry between the ligand hydroxyl group and imido-alkyl or alkylidene-alkyl tantalum precursors yields rare monometallic tantalum-NHC complexes, Ta(XtBu)(L)(CH2tBu)2 (X = N, CH), where the alkoxy-carbene ligand acts as a chelate...
January 9, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29314835/the-state-of-the-art-in-azaborine-chemistry-new-synthetic-methods-and-applications
#16
Zachary X Giustra, Shih-Yuan Liu
Boron-nitrogen heteroarenes hold great promise for practical application in many areas of chemistry. Enduring interest in realizing this potential has in turn driven perennial innovation with respect to these compounds' synthesis. This Perspective discusses in detail the most recent advances in methods pertaining to the preparation of BN-isosteres of benzene, naphthalene, and their derivatives. Additional focus is given to the progress enabled by these syntheses toward functional utility of such BN-heterocycles in biochemistry and pharmacology, materials science, and transition-metal-based catalysis...
January 9, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29303571/an-allosterically-regulated-four-state-macrocycle
#17
Andrea I d'Aquino, Ho Fung Cheng, Joaquín Barroso-Flores, Zachary S Kean, Jose Mendez-Arroyo, C Michael McGuirk, Chad A Mirkin
Macrocycles capable of host-guest chemistry are an important class of structures that have attracted considerable attention because of their utility in chemical separations, analyte sensing, signal amplification, and drug delivery. The deliberate design and synthesis of such structures are rate-limiting steps in utilizing them for such applications, and coordination-driven supramolecular chemistry has emerged as a promising tool for rapidly making large classes of such systems with attractive molecular recognition capabilities and, in certain cases, catalytic properties...
January 5, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29299856/malononitrile-dimer-as-a-privileged-reactant-in-design-and-skeletal-diverse-synthesis-of-heterocyclic-motifs
#18
REVIEW
Ahmad Shaabani, Seyyed Emad Hooshmand
Malononitrile dimer as a precursor reactant has been extensively applied in the diversity-oriented synthesis of various heterocyclic motifs, bis-heterocyclic compounds, fused heterocycle derivatives, bicyclic bridged heterocyclic scaffolds, and highly substituted carbocyclic compounds. These remarkable products were synthesized via various types of reactions, such as cycloaddition, cyclocondensation, cascade/domino/tandem reactions along with multi-component reactions. In addition, the flexibility and high reactivity of malononitrile dimer as a multi-functional reagent and its potential to the preparation of novel beneficial scaffolds as well as biologically active molecules signify it as a suitable building block in total synthesis, medicinal chemistry, and dyes...
January 3, 2018: Molecular Diversity
https://www.readbyqxmd.com/read/29273417/an-appraisal-on-synthetic-and-pharmaceutical-perspectives-of-pyrazolo-4-3-d-pyrimidine-scaffold
#19
REVIEW
Srinivasulu Cherukupalli, Girish A Hampannavar, Sampath Chinnam, Balakumar Chandrasekaran, Nisar Sayyad, Francis Kayamba, Rajeshwar Reddy Aleti, Rajshekhar Karpoormath
Pyrazolo[4,3-d]pyrimidine, a fused heterocycle bearing pyrazole and pyrimidine portions has gained a significant attention in the field of bioorganic and medicinal chemistry. Pyrazolo[4,3-d]pyrimidine derivatives have demonstrated numerous pharmacological activities particularly, anti-cancer, anti-infectious, phosphodiesterase inhibitors, adenosine antagonists and cytokinin antagonists etc. This review extensively unveils the synthetic and pharmacological diversity with special emphasis on structural variations around pyrazolo[4,3-d]pyrimidine scaffold...
October 25, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29243580/coumarins-as-promising-scaffold-for-the-treatment-of-age-related-diseases-an-overview-of-the-last-five-years
#20
Giovanna Lucia Delogu, Maria Joao Matos
Degenerative diseases are becoming increasingly prevalent with the aging of the human population. The twentieth century witnessed a significant demographic change in the industrialized world that is currently followed by a similar shift of life expectancy to upper age ranges in Asia, Africa, and Middle and South America. A rising tide of chronic age-dependent diseases will soon present serious challenges for these countries. Age-related diseases are commonly seen in older patients. More than 40% of adults 60 and older have a combination of risk factors known as metabolic syndrome, which increases the risk for developing degenerative disorders, and certain cancers...
December 14, 2017: Current Topics in Medicinal Chemistry
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