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Heterocyclic chemistry

Yufan Liang, Xiaheng Zhang, David W C MacMillan
Over the past three decades, considerable progress has been made in the development of methods to construct sp2 carbon-nitrogen (C-N) bonds using palladium, copper or nickel catalysis1,2 . However, the incorporation of alkyl substrates to form sp3 C-N bonds remains one of the major challenges in the field of cross-coupling chemistry. Here we demonstrate that the synergistic combination of copper catalysis and photoredox catalysis can provide a general platform from which to address this challenge. This cross-coupling system uses naturally abundant alkyl carboxylic acids and commercially available nitrogen nucleophiles as coupling partners...
June 20, 2018: Nature
Georgeta Serban, Oana Stanasel, Eugenia Serban, Sanda Bota
Pathogenic microorganisms are causative agents for different types of serious and even lethal infectious diseases. Despite advancements in medication, bacterial and fungal infections continue to be a growing problem in health care. As more and more bacteria become resistant to antibiotics used in therapy and an increasing number of invasive fungal species become resistant to current antifungal medications, there is considerable interest in the development of new compounds with antimicrobial activity. The compounds containing a heterocyclic ring play an important role among organic compounds with biological activity used as drugs in human and veterinary medicine or as insecticides and pesticides in agriculture...
2018: Drug Design, Development and Therapy
Dillon T Flood, Jordi C J Hintzen, Michael J Bird, Philip A Cistrone, Jason S Chen, Philip E Dawson
Facile synthesis of C-terminal thioesters is integral to native chemical ligation (NCL) strategies for chemical protein synthesis. Here we introduce a new method of mild peptide activation, which leverages SPPS on an established resin linker and a classical heterocyclic chemistry to convert C-terminal peptide hydrazides to their corresponding thioesters via an acyl pyrazole intermediate. Peptide hydrazides, synthesized on established trityl chloride resins, can be activated in solution with stoichiometric acetyl acetone (acac), readily proceed to the peptide acyl-pyrazole...
June 16, 2018: Angewandte Chemie
Anna Kryshchyshyn, Olexandra Roman, Andrii Lozynskyi, Roman Lesyk
This review presents the up to date development of fused thiopyranothiazoles that comprise one of the thiazolidine derivatives classes. Thiazolidine and thiazolidinone-related compounds belong to the widely studied heterocycles from a medicinal chemistry perspective. From the chemical point of view, they are perfect heterodienes to undergo hetero -Diels⁻Alder reaction with a variety of dienophiles, yielding regio- and diastereoselectively thiopyranothiazole scaffolds. The annealing of thiazole and thiopyran cycles in condensed heterosystem is a precondition for the “centers conservative” creation of the ligand-target binding complex and can promote a potential selectivity to biotargets...
June 14, 2018: Scientia Pharmaceutica
Suresh S Kumbar, Kallappa M Hosamani, Gangadhar C Gouripur, Shrinivas D Joshi
Recently, heterogeneous catalysts have been explored eximiously in the synthesis of heterocyclic compounds. Therefore, here we used solid-supported heterogeneous silica sulfuric acid as a catalyst for the synthesis of Schiff's base of 3-chloroformylcoumarin in view of simplified procedure, reusability and acceptable efficiency, which are required in organic synthesis. An efficient and facile methodology is preferred for synthesis of a class of chromeno-3-substituted derivatives ( 1a-1l ) with good yields. The molecular docking results showed excellent binding interactions with the Mycobacterium tuberculosis InhA-D148G mutant (PDB: 4DQU)...
May 2018: Royal Society Open Science
Boris Letribot, Régis Delatouche, Hervé Rouillard, Antoine Bonnet, Jean-René Chérouvrier, Lisianne Domon, Thierry Besson, Valérie Thiéry
Alkylidene oxindoles are important functional moieties and building blocks in pharmaceutical and synthetic chemistry. Our interest in biologically active compounds focused our studies on the synthesis of novel oxindoles, bearing on the exocyclic double bond at the C8, CN, and S groups. Extending the potential applications of Appel’s salt, we developed a new synthetic approach by investigating the reactions of C5-substituted 2-oxindoles with 4,5-dichloro-1,2,3-dithiazolium chloride (Appel’s salt) to give original ( Z )-3-(4-chloro-5 H -1,2,3-dithiazol-5-ylidene)indolin-2-one derivatives, and new 2-mercapto-(2-oxoindolin-3-ylidene)acetonitriles via a dithiazole ring-opening reaction...
June 8, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Krisztián Tóth, Georg Höfner, Klaus T Wanner
In this study, we present the synthesis and structure-activity relationships (SAR) of novel N-substituted nipecotic acid derivatives closely related to (S)-SNAP-5114 (2) in the pursuit of finding new and potent mGAT4 selective inhibitors. By the use of iminium ion chemistry, a series of new N-substituted nipecotic acid derivatives containing a variety of heterocycles, and an alkyne spacer were synthesized. Biological evaluation of the prepared compounds showed, how the inhibitory potency and subtype selectivity for the murine GABA transporters (mGATs) were influenced by the performed modifications...
June 1, 2018: Bioorganic & Medicinal Chemistry
Mohammad Bayat, Zeinab Amiri
This review characterizes the multicomponent reactions of acenaphthoquinone as building blocks for the synthesis of a variety of heterocyclic compounds with medicinal chemistry interest. There is a wide range of reactions that include acenaphthoquinone in the synthesis of heterocyclic compounds. Also this review gives an overview spirocyclic compounds has important applications in pharmacological during the period from 2000 to 2017. Spiro compounds having cyclic structures fused at a central carbon are of recent interest due to their interesting adjustable overall qualities and their structural implications on biological systems...
June 5, 2018: Topics in Current Chemistry (Journal)
Taghreed H El-Sayed, Asmaa Aboelnaga, Mohamed A El-Atawy, Mohamed Hagar
In the last years, numerous protocols have been published using ball milling for organic synthesis. Compared to other methods such as microwave or ultrasound irradiation and ionic liquids, ball mill chemistry is an economical, and ecofriendly method in organic synthesis that is rather underrepresented in the knowledge of organic chemists. The aim of this review is to explore the advantages of the application of ball milling in synthesis of N -heterocyclic compounds.
June 4, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Chumki Banik, Michael Lawrinenko, Santanu Bakshi, David A Laird
The capacity of biochars to adsorb ionic contaminants is strongly influenced by biochar surface chemistry. We studied the effects of biomass feedstock type, pyrolysis temperature, reaction media pH, and AlCl pre-pyrolysis feedstock treatments on biochar anion exchange capacity (AEC), cation exchange capacity (CEC), point of zero net charge (PZNC), and point of zero salt effect (PZSE). We used the relationship between PZNC and PZSE to probe biochar surfaces for the presence of unstable (hydrolyzable) surface charge functional groups...
May 2018: Journal of Environmental Quality
Nikolaus Gorgas, Karl Kirchner
Sustainable processes that utilize nontoxic, readily available, and inexpensive starting materials for organic synthesis constitute a major objective in modern chemical research. In this context, it is highly important to perform reactions under catalytic conditions and to replace precious metal catalysts by earth-abundant nonprecious metal catalysts. In particular, iron and manganese are promising candidates, as these are among the most abundant metals in the earth's crust, are inexpensive, and exhibit a low environmental impact...
June 4, 2018: Accounts of Chemical Research
Wenlong Wang, Lifeng Cui, Peng Sun, Lijun Shi, Chengtao Yue, Fuwei Li
With the continuous development of N-heterocyclic carbene (NHC) chemistry during the past decade, NHC metal complexes have gained wide applications in the research field of organometallic catalysis. The recycling and reuse of NHC metal complexes, which have undergone continuous expansion and diversification, can enhance their catalytic performance, extend their range of application, and afford new routes to green chemistry. Taking NHC metal complex catalysts as the main topic, this review intends to present a comprehensive study of recycling strategies of organometallic catalysts...
May 31, 2018: Chemical Reviews
Harina Amer Hamzah, William Gee, Paul Raithby, Simon Teat, Mary Mahon, Andrew David Burrows
The Mannich reaction of the zirconium MOF [Zr6O4(OH)4(bdc-NH2)6] (UiO-66-NH2, bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) with paraformaldehyde and pyrazole, imidazole or 2-mercaptoimidazole led to post-synthetic modification (PSM) through C-N bond formation. The reaction with imidazole (Him) goes to completion whereas those with pyrazole (Hpyz) and 2-mercaptoimidazole (HimSH) give up to 41% and 36% conversion, respectively. The BET surface areas for the Mannich products are reduced from that of UiO-66-NH2, but the compounds show enhanced selectivity for adsorption of CO2 over N2 at 273 K...
May 29, 2018: Chemistry: a European Journal
Leslie Reguera, Yanira Méndez, Ana R Humpierre, Oscar Valdés, Daniel G Rivera
Multicomponent reactions (MCRs) encompass an exciting class of chemical transformations that have proven success in almost all fields of synthetic organic chemistry. These convergent procedures incorporate three or more reactants into a final product in one pot, thus combining high levels of complexity and diversity generation with low synthetic cost. Striking applications of these processes are found in heterocycle, peptidomimetic, and natural product syntheses. However, their potential in the preparation of large macro- and biomolecular constructs has been realized just recently...
May 25, 2018: Accounts of Chemical Research
Pervaiz Ali Channar, Aamer Saeed, Fayaz Ali Larik, Bakhtawar Batool, Saima Kalsoom, M M Hasan, Mauricio F Erben, Hesham R El-Seedi, Musrat Ali, Zaman Ashraf
Aryl pyrazoles are well recognized class of heterocyclic compounds found in several commercially available drugs. Owing to their significance in medicinal chemistry, in this current account we have synthesized a series of suitably substituted aryl pyrazole by employing Suzuki cross-coupling reaction. All compounds were evaluated for inhibition of mushroom tyrosinase enzyme both in vitro and in silico. Compound 3f (IC50  = 1.568 ± 0.01 µM) showed relatively better potential compared to reference kojic acid (IC50  = 16...
April 30, 2018: Bioorganic Chemistry
Tsuyoshi Kato, Masayuku Nakagaki, Antoine Baceiredo, Shigeyoshi Sakaki
Although oxidative addition (O.A.) and reductive elimination (R.E.) are exceedingly important processes in organometallic chemistry, such processes are still extremely rare for main group element species. Here we report a theoretical study on the reaction of phosphine-stabilized silylenes with silanes which proceeds via reversible O.A./R.E. at room temperature. Of particular interest, this theoretical approach highlights the important role of the ligand, which can greatly affect kinetics and energy balance of the reaction...
May 22, 2018: Chemistry: a European Journal
Lingling Zhang, Guoting Zhang, Yongli Li, Shengchun Wang, Aiwen Lei
Constructing carbon-carbon bonds through oxidative cross-coupling between two hydrocarbon compounds is regarded as a foundational issue in green chemistry. High atom-economy and mild conditions are long term pursued goals in this field. Herein, we developed a visible-light mediated direct cross-coupling between N-heterocycles and aldehydes without the requirement of a photocatalyst. Several N-heterocycles afforded the acylation products with aromatic or aliphatic aldehydes in good yields. The reaction can be conducted under room temperature and easily scaled up...
May 21, 2018: Chemical Communications: Chem Comm
Hansjörg Grützmacher, José Goicoechea
Likely the first synthesis of the phosphaethynolate anion, PCO-, was performed already in 1894 when NaPH2 was reacted with CO in an attempt to make Na(CP) under elimination of water. This reaction was repeated only 117 years later when it was discovered that Na(OCP) and H2 are the products of this remarkable transformation. Li(OCP) was synthesized and fully characterized in 1992 but this salt proved to be too unstable to allow a detailed investigation. Remarkably, it needs the heavier analogues of this lithium salt, Na(OCP) and K(OCP), which are remarkably stable and can be even dissolved in water, to fully explore fully the chemistry of this new functional group...
May 17, 2018: Angewandte Chemie
Jian Wang, Ming Lang, Qianfa Jia
-Pyones are frequently observed as the core in numerous natural products and biologically important molecules. They have exhibited promising biological activities, such as anti-HIV, antimicrobial, antifungal, telomerase inhibition, pheromonal, androgen, cardiotonic, neurotoxic and phytotoxic effects. In medicinal chemistry, α-pyones often serve as convenient precursors for the assembly of other medicinal important structures. Therefore, the development of an efficient synthetic protocol for the construction of diversified -pyrone derivatives tends to be interesting and highly demanded...
May 16, 2018: Chemistry, An Asian Journal
Hayoung Song, Hyunho Kim, Eunsung Lee
Herein, a coumaraz-2-on-4-ylidene (1) as a new example of ambiphilic N-heterocyclic carbenes with fine tunable electronic properties is reported. The N-carbamic and aryl groups on carbene carbon provide exceptionally high electrophilicity and nucleophilicity simultaneously to the carbene center, as evidenced by the 77Se NMR chemical shifts of their selenoketone derivatives and the CO stretching strengths of their rhodium carbonyl complexes. Since the precursors of 1 could be synthesized from various functionalized Schiff bases in a practical and scalable manner, the electronic properties of 1 can be fine-tuned in quantitative and predictable way using the Hammett σ constant of the functional groups on aryl ring...
May 16, 2018: Angewandte Chemie
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