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Heterocyclic chemistry

Sana Tariq, K Somakala, Mohd Amir
Quinoxaline, a fused heterocycle of benzene and pyrazine rings has gained considerable attention in the field of contemporary medicinal chemistry. The moiety is of substantial importance because of its wide array of pharmacological activities viz. anti-cancer, antimalarial, anti-inflammatory, antimicrobial, anti-HIV etc. Diversely substituted quinoxalines are important therapeutic agents in the pharmaceutical industry. This review focusses on the quinoxaline derivatives developed during the last decennial period and their biomedical applications...
November 24, 2017: European Journal of Medicinal Chemistry
Soroush Sardari, Samaneh Feizi, Ali Hossein Rezayan, Parisa Azerang, Seyyed Mohammad Shahcheragh, Ghazaleh Ghavami, Azizollah Habibi
Thiosemicarbazides are potent intermediates for the synthesis of pharmaceutical and bioactive materials and thus, they are used extensively in the field of medicinal chemistry. The imine bond (-N=CH-) in this compounds are useful in organic synthesis, in particular for the preparation of heterocycles and non-natural β-aminoacids. In this paper the synthesis of some new thiosemicarbazide derivatives by condensation reaction of various aldehydes or ketones with 4-phenylthiosemicarbazide or thiosemicarbazide is reported...
2017: Iranian Journal of Pharmaceutical Research: IJPR
Christopher J Schwalen, Graham A Hudson, Simone Kosol, Nilkamal Mahanta, Gregory L Challis, Douglas A Mitchell
The bottromycins belong to the ribosomally synthesized and posttranslationally modified peptide (RiPP) family of natural products. Bottromycins exhibit unique structural features, including a hallmark macrolactamidine ring and thiazole heterocycle for which divergent members of the YcaO superfamily have been biosynthetically implicated. Here we report the in vitro reconstitution of two YcaO proteins, BmbD and BmbE, responsible for the ATP-dependent cyclodehydration reactions that yield thiazoline- and macrolactamidine-functionalized products, respectively...
December 4, 2017: Journal of the American Chemical Society
Hyo-Joong Kim, Steven A Benner
Under the "RNA World" hypothesis, an early episode of natural history on Earth used RNA as the only genetically encoded molecule to catalyze steps in its metabolism catalysis. This, according to the hypothesis, included RNA catalysts that used RNA cofactors. However, the RNA World hypothesis places special demands on prebiotic chemistry, which must now deliver not only four ribonucleosides, but also must deliver the "functional" portion of these RNA cofactors. While some (e.g. methionine) present no particular challenges, nicotinamide ribose is special...
November 30, 2017: Chemistry: a European Journal
Tom van Dijk, J Chris Slootweg, Koop Lammertsma
Nitrilium ions have been well-established in organic chemistry for many decades, but recent developments show them to be far more versatile than hitherto recognized. They are known as stable salts, can be generated in situ, or are present as transient intermediates. We provide a succinct, but comprehensive review on the synthesis, stability, and reactivity of nitrilium ions as synthons for imines, their use in the synthesis of a large spectrum of heterocycles, and their reactions with transition metal complexes...
November 30, 2017: Organic & Biomolecular Chemistry
Esteban Vargas, Fernando Echeverri, Iván D Vélez, Sara M Robledo, Wiston Quiñones
The S-containing heterocyclic compounds benzothiopyrans or thiochromones stand out as having promising biological activities due to their structural relationship with chromones (benzopyrans), which are widely known as privileged scaffolds in medicinal chemistry. In this work, we report the synthesis of 35 thiochromone derivatives and the in vitro antileishmanial and cytotoxic activities. Compounds were tested against intracellular amastigotes of Leishmania panamensis and cytotoxic activity against human monocytes (U-937 ATCC CRL-1593...
November 29, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Bai-Jing Peng, Wen-Ting Wu, And Shyh-Chyun Yang
Given the importance of heterocycle indole derivatives, much effort has been directed toward the development of methods for functionalization of the indole nucleus at N1 and C3 sites. Moreover, the platinum-catalyzed allyation of nucleophiles was an established and efficient way, which has been applied to medicinal and organic chemistry. In our research, the platinum-catalyzed 2,3-disubstitued indoles with allylic acetates was investigated under different conditions. Herein, we established a simple, convenient, and efficient method, which afforded high yield of allylated indoles...
November 29, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Martina Tireli, Silvija Maračić, Stipe Lukin, Marina Juribašić Kulcsár, Dijana Žilić, Mario Cetina, Ivan Halasz, Silvana Raić-Malić, Krunoslav Užarević
Copper-catalyzed mechanochemical click reactions using Cu(II), Cu(I) and Cu(0) catalysts have been successfully implemented to provide novel 6-phenyl-2-(trifluoromethyl)quinolines with a phenyl-1,2,3-triazole moiety at O-4 of the quinoline core. Milling procedures proved to be significantly more efficient than the corresponding solution reactions, with up to a 15-fold gain in yield. Efficiency of both solution and milling procedures depended on the p-substituent in the azide reactant, resulting in H < Cl < Br < I reactivity bias...
2017: Beilstein Journal of Organic Chemistry
Jacob M Ganley, Charles S Yeung
Indazoles represent a privileged scaffold in medicinal chemistry. In the presence of strong base, however, N-protected indazoles are prone to an undesirable ring-opening reaction to liberate ortho-aminobenzonitriles. By employing unprotected indazoles with a free N-H bond, isomerization is averted since the heterocycle is deprotonated in situ. We herein report a functional group tolerant and robust C-S couplings of bromo-indazoles with thiols of varying electronic nature in the presence of lithium bis(trimethylsilyl)amide at elevated temperatures...
November 27, 2017: Journal of Organic Chemistry
Muthu Thangaraj, Robert Moonsamy Gengan, Bibhuti Ranjan, Ramesh Muthusamy
A series of quinoline based peptides were synthesized by a one-pot reaction through Ugi-four component condensation of lipoic acid, cyclohexyl isocyanide, aniline derivatives and 2-methoxy quinoline-3-carbaldehyde derivatives under microwave irradiation. The products were obtained in excellent yields and high purity. Solvent optimization and the effect of microwave irradiation with various powers were also observed. All the synthesized compounds were characterized by FTIR, NMR spectral data and elemental analysis...
November 16, 2017: Journal of Photochemistry and Photobiology. B, Biology
Wen-Bo Shen, Qing Sun, Long Li, Xin Liu, Bo Zhou, Juan-Zhu Yan, Xin Lu, Long-Wu Ye
Gold-catalyzed intermolecular alkyne oxidation by an N-O bond oxidant has proven to be a powerful method in organic synthesis during the past decade, because this approach would enable readily available alkynes as precursors in generating α-oxo gold carbenes. Among those, gold-catalyzed oxidative cyclization of dialkynes has received particular attention as this chemistry offers great potential to build structurally complex cyclic molecules. However, these alkyne oxidations have been mostly limited to noble metal catalysts, and, to our knowledge, non-noble metal-catalyzed reactions such as diyne oxidations have not been reported...
November 23, 2017: Nature Communications
Kate Lauder, Anita Toscani, Nicolò Scalacci, Daniele Castagnolo
Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A(3) couplings and C-H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses...
November 22, 2017: Chemical Reviews
Dillon P Cogan, Graham A Hudson, Zhengan Zhang, Taras V Pogorelov, Wilfred A van der Donk, Douglas A Mitchell, Satish K Nair
The [4+2] cycloaddition reaction is an enabling transformation in modern synthetic organic chemistry, but there are only limited examples of dedicated natural enzymes that can catalyze this transformation. Thiopeptides (or more formally thiazolyl peptides) are a class of thiazole-containing, highly modified, macrocyclic secondary metabolites made from ribosomally synthesized precursor peptides. The characteristic feature of these natural products is a six-membered nitrogenous heterocycle that is assembled via a formal [4+2] cycloaddition between two dehydroalanine (Dha) residues...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
Mikhail Krasavin, Anton Shetnev, Tatyana Sharonova, Sergey Baykov, Tiziano Tuccinardi, Stanislav Kalinin, Andrea Angeli, Claudiu T Supuran
A series of novel aromatic primary sulfonamides decorated with diversely substituted 1,2,4-oxadiazole periphery groups has been prepared using a parallel chemistry approach. The compounds displayed a potent inhibition of cytosolic hCA II and membrane-bound hCA IX isoforms. Due to a different cellular localization of the two target enzymes, the compounds can be viewed as selective inhibition tools for either isoform, depending on the cellular permeability profile. The SAR findings revealed in this study has been well rationalized by docking simulation of the key compounds against the crystal structures of the relevant hCA isoforms...
October 16, 2017: Bioorganic Chemistry
Saptarshi Biswas, Shuwen Ma, Stefano Nuzzo, Brendan Twamley, Andrew T Russell, James A Platts, František Hartl, Robert J Baker
A series of complexes [Et4N][Ln(NCS)4(H2O)4] (Ln = Pr, Tb, Dy, Ho, Yb) have been structurally characterized, all showing the same structure, namely a distorted square antiprismatic coordination geometry, and the Ln-O and Ln-N bond lengths following the expected lanthanide contraction. When the counterion is Cs(+), a different structural motif is observed and the eight-coordinate complex Cs5[Nd(NCS)8] isolated. The thorium compounds [Me4N]4[Th(NCS)7(NO3)] and [Me4N]4[Th(NCS)6(NO3)2] have been characterized, and high coordination numbers are also observed...
November 16, 2017: Inorganic Chemistry
Zhijun Li, Kim A Munro, Iraklii I Ebralidze, Mina R Narouz, J Daniel Padmos, Hongxia Hao, Cathleen M Crudden, J Hugh Horton
Surface plasmon resonance (SPR)-based biosensing is a powerful tool to study the recognition processes between biomole-cules in real-time without need for labels. The use of thiol chemistry is a critical component in surface functionalization of various SPR biosensor surfaces on gold. However, its use is hampered by the high propensity for oxidation of the gold-thiol linkage even in ambient atmosphere, resulting in a short lifetime of SPR sensor chips unless strict precautions are taken. Herein, we describe an approach to overcome this limitation by employing highly robust self-assembled monolayers (SAMs) of alkylated N-heterocyclic carbenes (NHCs) on gold...
November 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Olga Taran, Chenrui Chen, Tolulope O Omosun, Ming-Chien Hsieh, Allisandra Rha, Jay T Goodwin, Anil K Mehta, Martha A Grover, David G Lynn
The RNA world hypothesis simplifies the complex biopolymer networks underlining the informational and metabolic needs of living systems to a single biopolymer scaffold. This simplification requires abiotic reaction cascades for the construction of RNA, and this chemistry remains the subject of active research. Here, we explore a complementary approach involving the design of dynamic peptide networks capable of amplifying encoded chemical information and setting the stage for mutualistic associations with RNA...
December 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Larizza Hellen Santana Matos, Flávia Teixeira Masson, Luiz Alberto Simeoni, Mauricio Homem-de-Mello
Dihydropyrimidinones are heterocycles with a pyrimidine moiety in the ring nucleus, which, in recent decades, have aroused interest in medicinal chemistry due to alleged versatile biological activity. In this systematic review, we describe the currently published activities of dihydropyrimidinone derivatives. Between 1990 and December 31st, 2016, 115 articles outlined biological activities or toxicity of DHPM derivatives, 12 of those involved in vivo experiments. The main activities associated with this class of compounds are antitumoral (43 articles), anti-inflammatory (12 articles), antibacterial (20 articles) and calcium channel antagonism/inhibition (14 articles)...
October 31, 2017: European Journal of Medicinal Chemistry
Pavel S Gribanov, Gleb A Chesnokov, Maxim A Topchiy, Andrey F Asachenko, Mikhail S Nechaev
A general method of the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by Suzuki-Miyaura cross-coupling from 4- and 5-halo-1,2,3-triazoles is reported. The reaction is mediated by an expanded-ring N-heterocyclic carbene palladium complex in water. The developed reaction protocol meets the requirements of "green chemistry". Cross-coupling of 4- and 5-chlorotriazoles is reported for the first time.
November 22, 2017: Organic & Biomolecular Chemistry
Grzegorz Mlostoń, Heinz Heimgartner
The scope of applications of dialkyl dicyanofumarates and maleates as highly functionalized electron-deficient dipolarophiles, dienophiles and Michael acceptors is summarized. The importance for the studies on reaction mechanisms of cycloadditions is demonstrated. Multistep reactions with 1,2-diamines and β-aminoalcohols leading to diverse five- and six-membered heterocycles are discussed. Applications of dialkyl dicyanofumarates as oxidizing agents in the syntheses of disulfides and diselenides are described...
2017: Beilstein Journal of Organic Chemistry
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