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Heterocyclic chemistry

Liu-Zhu Yu, Kai Chen, Zi-Zhong Zhu, Min Shi
During the past several years, functionalized alkylidenecyclopropanes (FACPs) have attracted intensive attention in synthetic chemistry. Many interesting transformations of FACPs have been developed to synthesize a lot of structurally diverse and valuable polycyclic and heterocyclic compounds. This review will classify FACPs into aryl-FACPs, alkyl-FACPs and ring-FACPs for the first time, and recent interesting chemical transformations in these research fields will be included, respectively, from 2011. Moreover, we will pay more attention to the clarification of the reaction mechanism, in which the C-C bond cleavage of alkylidenecyclopropanes (ACPs) will be emphasized...
May 17, 2017: Chemical Communications: Chem Comm
Alberto Hernán-Gómez, Alan R Kennedy, Eva Hevia
Combining alkali-metal-mediated metalation (AMMM) and N-heterocyclic carbene (NHC) chemistry, a novel C-N bond activation and ring-opening process is described for these increasingly important NHC molecules, which are generally considered robust ancillary ligands. Here, mechanistic investigations on reactions of saturated NHC SIMes (SIMes=[:C{N(2,4,6-Me3 C6 H2 )CH2 }2 ]) with Group 1 alkyl bases suggest this destructive process is triggered by lateral metalation of the carbene. Exploiting co-complexation and trans-metal-trapping strategies with lower polarity organometallic reagents (Mg(CH2 SiMe3 )2 and Al(TMP)iBu2 ), key intermediates in this process have been isolated and structurally defined...
May 10, 2017: Angewandte Chemie
Hideki Yorimitsu
A new class of Pummerer chemistry has emerged as a powerful tool in organic synthesis. The new technology consists of a beautiful cascade of an interrupted Pummerer reaction and the subsequent [3,3] sigmatropic rearrangement. The interrupted Pummerer reactions of alkenyl or aryl sulfoxides with unsaturated nucleophiles such as allylic silanes, ketones, and phenols provide sulfonium intermediates, which are ready to undergo smooth charge-accelerated [3,3] sigmatropic rearrangement with excellent to exclusive regioselectivity...
May 10, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
S Arshadi, E Vessally, L Edjlali, R Hosseinzadeh-Khanmiri, E Ghorbani-Kalhor
Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines...
2017: Beilstein Journal of Organic Chemistry
Marina Uzelac, Alan R Kennedy, Eva Hevia
Merging two topical themes in main-group chemistry, namely, cooperative bimetallics and frustrated-Lewis-pair (FLP) activity, this Forum Article focuses on the cooperativity-induced outcomes observed when the tris(alkyl)gallium compound GaR3 (R = CH2SiMe3) is paired with the lithium amide LiTMP (TMP = 2,2,6,6-tetramethylpiperidide) or the sterically hindered N-heterocyclic carbene (NHC) 1,3-bis(tert-butyl)imidazol-2-ylidene (I(t)Bu). When some previously published work are drawn together with new results, unique tandem reactivities are presented that are driven by the steric mismatch between the individual reagents of these multicomponent reagents...
May 9, 2017: Inorganic Chemistry
Saima Perveen, Zhifei Zhao, Guoxiang Zhang, Jian Liu, Muhammad Anwar, Xinqiang Fang
1,2-Dihydronaphthalenes are important molecules in both medicinal and synthetic chemistry, but methods for the catalytic asymmetric construction of this class of molecules are limited. The diastereo- and enantioselective N-heterocyclic carbene-catalyzed cascade annulation reactions using benzodiketones and enals under oxidative conditions, which afford a variety of 1,2-dihydronaphthalenes with two adjacent stereocenters in up to 99% yield, with >20:1 dr, and up to 99% ee, are reported. Furthermore, the product can be easily transformed to a series of useful compounds such as alcohol, amide, and epoxide...
May 9, 2017: Organic Letters
Zhe-Chen Wang, Veronica M Bierbaum
The existence of heterocyclic aromatic anions in extraterrestrial environments, such as the upper atmosphere of Titan, has been recently confirmed by data from the Cassini spacecraft. Nitrogen and oxygen atoms are also common species in the ionospheres of planets and moons and in the interstellar medium. In the current work, we extend previous studies to explore the reactivity of five-membered ring aromatic anions that contain nitrogen, oxygen, or sulfur (deprotonated pyrrole, furan, and thiophene) with N and O atoms both experimentally and computationally...
May 3, 2017: Journal of Physical Chemistry. A
Phan T Truong, Eric M Gale, Stephen P Dzul, Timothy L Stemmler, Todd C Harrop
Ni-containing superoxide dismutase (NiSOD) represents an unusual member of the SOD family due to the presence of oxygen-sensitive Ni-SCys bonds at its active site. Reported in this account is the synthesis and properties of the Ni(II) complex of the N3S2 ligand [N3S2(Me2)](3-) ([N3S2(Me2)](3-) = deprotonated form of 2-((2-mercapto-2-methylpropyl)(pyridin-2-ylmethyl)amino)-N-(2-mercaptoethyl)acetamide), namely Na[Ni(N3S2(Me2))] (2), as a NiSOD model that features sterically robust gem-(CH3)2 groups on the thiolate α-C positioned trans to the carboxamide...
May 1, 2017: Inorganic Chemistry
Rajnikanth Sunke, Suresh Babu Nallapati, Jetta Sandeep Kumar, K Shiva Kumar, Manojit Pal
As a privileged class of heterocyclic compounds N-heteroarenes have found enormous applications in many areas including medicinal/pharmaceutical chemistry and drug discovery. Consequently, a wide variety of methods have been reported for their synthesis. While not free from their own limitations the AlCl3 mediated methods appeared to have some particular advantages in preparing a number of useful N-heteroarenes. Besides the famous Friedel-Crafts (FC) alkylation/acylation reactions one such example is AlCl3-induced heteroarylation of arenes and heteroarenes (FC arylation type reactions) that can be used to prepare a certain class of N-heteroarenes in an operationally simple, efficient and cost effective manner...
May 16, 2017: Organic & Biomolecular Chemistry
Lisa Suntrup, Sinja Klenk, Johannes Klein, Sebastian Sobottka, Biprajit Sarkar
Bidentate ligands containing at least one triazole or triazolylidene (mesoionic carbene, MIC) unit are extremely popular in contemporary chemistry. One reason for their popularity is the similarities as well as differences in the donor/acceptor properties that these ligands display in comparison to their pyridine or other N-heterocyclic carbene counterparts. We present here seven rhenium(I) carbonyl complexes where the bidentate ligands contain combinations of pyridine/triazole/triazolylidene. These are the first examples of rhenium(I) complexes with bidentate 1,2,3-triazol-5-ylidene-containing ligands...
April 21, 2017: Inorganic Chemistry
Melanie W Lui, Olena Shynkaruk, Meagan S Oakley, Regina Sinelnikov, Robert McDonald, Michael J Ferguson, Al Meldrum, Mariusz Klobukowski, Eric Rivard
By investigating the coordination chemistry of a neutral N-heterocyclic olefin phosphine ligand, a new digold(i) chloride complex was discovered, demonstrating that mixed element (P/C) donor sites can be accessed at the same time. However attempts to extend this strategy for the preparation of heterobimetallic complexes featuring copper(i) and gold(i) centers with this mixed donor ligand were unsuccessful. The related monometallic copper(i) and gold(i) iodide complexes were discovered to be emissive in the solid state...
May 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Navriti Chadha, Om Silakari
Indoles constitute extensively explored heterocyclic ring systems with wide range of applications in pathophysiological conditions that is, cancer, microbial and viral infections, inflammation, depression, migraine, emesis, hypertension, etc. Presence of indole nucleus in amino acid tryptophan makes it prominent in phytoconstituents such as perfumes, neurotransmitters, auxins (plant hormones), indole alkaloids etc. The interesting molecular architecture of indole makes them suitable candidates for the drug development...
April 5, 2017: European Journal of Medicinal Chemistry
Lukas Omann, C David F Königs, Hendrik F T Klare, Martin Oestreich
Cooperative catalysis has attracted tremendous attention in recent years, emerging as a key strategy for the development of novel atom-economic and environmentally more benign catalytic processes. In particular, Noyori-type complexes with metal-nitrogen bonds have been extensively studied and evolved as privileged catalysts in hydrogenation chemistry. In contrast, catalysts containing metal-sulfur bonds as the reactive site are out of the ordinary, despite their abundance in living systems, where they are assumed to play a key role in biologically relevant processes...
April 13, 2017: Accounts of Chemical Research
Xi Mao, Tao Tong, Senbao Fan, Liting Fang, Jingyi Wu, Xiaoxia Wang, Honglan Kang, Xin Lv
A novel and expedient one-pot synthesis of thiazino[2,3,4-hi]indole derivatives from o-haloaryl enamines and o-bromothiophenols has been developed. The tandem oxidative coupling/heteroannulation reactions exhibit high selectivity and good efficiency. The polycyclic heterocyclic products obtained might be useful in medicinal chemistry and materials science.
April 12, 2017: Chemical Communications: Chem Comm
Wan Jung Kim, Keith Korthals, Suhua Li, Christine Le, Jaroslaw Kalisiak, K Barry Sharpless, Valery V Fokin, Yukiko Miyamoto, Lars Eckmann
Giardia lamblia is an important and ubiquitous cause of diarrheal disease. The primary agents in the treatment of giardiasis are nitroheterocyclic drugs, particularly the imidazoles metronidazole and tinidazole, and the thiazole, nitazoxanide. Although these drugs are generally effective, treatment failures occur in up to 20% of cases and resistance has been demonstrated in vivo and in vitro. Prior work had suggested that side chain modifications of the imidazole core can lead to effective new 5-nitroimidazole drugs that can combat nitro drug resistance, but the full potential of nitroheterocycles other than imidazole to yield effective new antigiardial agents has not been explored...
April 10, 2017: Antimicrobial Agents and Chemotherapy
Jitendra K Bera, Kuldeep Singh, Abir Sarbajna, Indranil Dutta, Pragati Pandey
A Ni(II) complex 1 containing pyridyl- and hydroxy-functionalized N-heterocyclic carbenes (NHC) is synthesized and its catalytic utility for selective nitrile hydration to amide under base-free condition is evaluated. The title compound exploits hemilabile pyridyl unit to interact with a catalytically relevant water molecule via hydrogen-bonding and promote nucleophilic water attack to the nitrile. A wide variety of nitriles are hydrated to the corresponding amides including pharmaceutical drugs Rufinamide, Rifater and Piracetam...
April 7, 2017: Chemistry: a European Journal
Sambasivarao Kotha, Chandravathi Chakkapalli
Indole and its derivatives captured the attention of organic chemists due to their applications in medicinal chemistry. The examples covered here are intricate polycyclic indole derivatives and these include: azapolyquinanes, cyclophanes, spirocycles and other heterocycles. We found that deep eutectic mixture such as L-(+)-tartaric acid (TA) and dimethyl urea (DMU) is useful to prepare complex unnatural indole derivatives. These conditions from time to time produced indole derivatives which are not possible by conventional methods...
April 5, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Emanuel Hernández-Núñez, Hugo Tlahuext, Rosa Moo-Puc, Diego Moreno, María Ortencia González-Díaz, Gabriel Navarrete Vázquez
Parasitic diseases are a public health problem affecting millions of people worldwide. One of the scaffolds used in several drugs for the treatment of parasitic diseases is the benzimidazole moiety, a heterocyclic aromatic compound. This compound is a crucial pharmacophore group and is considered a privileged structure in medicinal chemistry. In this study, the benzimidazole core served as a model for the synthesis of a series of 2-(2-amino-5(6)-nitro-1H-benzimidazol-1-yl)-N-arylacetamides 1-8 as benznidazole analogues...
April 4, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Siddappa A Patil, Shivaputra A Patil, Renukadevi Patil
Macrocyclic chemistry is one of the emerging research areas in the chemical science. Macrocyclic compounds continue to attract significant attention due to their numerous possible applications particularly in the areas like biology, catalysis and industry. This review article summarizes the developments and advances in synthesis and medicinal applications of macrocyclic compounds derived from (benz)imidazole- and indole-based heterocycles. Important medicinal applications of (benz)imidazole- and indole-based macrocycles include antimicrobial and anticancer activities...
April 2017: Chemical Biology & Drug Design
Oleg I Artyushin, Elena V Sharova, Natalya M Vinogradova, Galina K Genkina, Aleksandra A Moiseeva, Zinaida S Klemenkova, Iana R Orshanskaya, Anna A Shtro, Renata A Kadyrova, Vladimir V Zarubaev, Olga I Yarovaya, Nariman F Salakhutdinov, Valery K Brel
A series of seventeen tetrazole derivatives of 1,7,7-trimethyl-[2.2.1]bicycloheptane were synthesized using click chemistry methodology and characterized by spectral data. Studies of cytotoxicity and in vitro antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1) in MDCK cells of the compounds obtained were performed. The structure-activity relationship analysis suggests that to possess virus-inhibiting activity, the compounds of this group should bear oxygen atom with a short linker (C2-C4), either as a hydroxyl group (18, 19, 29), keto-group (21) or as a part of a heterocycle (24)...
March 22, 2017: Bioorganic & Medicinal Chemistry Letters
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