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Heterocyclic chemistry

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
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 due to its application to pharmaceuticals, agrochemicals, and late stage functionalization reactions on complex molecules. Based on 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 site selectivity of direct C-H functionalization in a number of heterocycles and identify general trends observed across heterocycle classes...
July 18, 2017: Journal of the American Chemical Society
Jin Chang, Hongyu Ren, Mingxia Zhao, Yan Chong, Wenwen Zhao, Yong He, Yunling Zhao, Huabei Zhang, Chuanmin Qi
4-anilinoquinazoline-based derivatives represent an attractive scaffold for small molecular EGFR-TKIs in the field of medicinal chemistry. A series of novel heterocyclic substituted derivatives have been designed, synthesized and evaluated their antitumor bioactivities as potential EGFR-TKIs. Most of the new compounds exhibited certain efficient inhibition potency for proliferation of a panel of five human cancer cells with IC50 values at the low micromolar level, and some of them possessed good broad-spectrum inhibition activities, compared to Gefitinib...
July 4, 2017: European Journal of Medicinal Chemistry
Kenneth A Jacobson, Stefania Merighi, Katia Varani, Pier Andrea Borea, Stefania Baraldi, Mojgan Aghazadeh Tabrizi, Romeo Romagnoli, Pier Giovanni Baraldi, Antonella Ciancetta, Dilip K Tosh, Zhan-Guo Gao, Stefania Gessi
The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics...
July 6, 2017: Medicinal Research Reviews
Tao Liu, Jun Tian, Wen-Chao Gao, Hong-Hong Chang, Qiang Liu, Xing Li, Wen-Long Wei
An acid-catalyzed intermolecular sulfenoamination reaction of alkenes is developed with sulfonamides as the nitrogen source and N-sulfanylsuccinimides as the sulfur source. This methodology provides a straightforward and general way to synthesize various β-sulfonylamino sulfides with high regio- and diastereoselectivity. The developed method was coupled with intramolecular C-N coupling in a one-pot procedure to afford a series of dihydrobenzothiazine derivatives, a kind of important heterocycle used as biologically active compounds in medicinal chemistry...
July 19, 2017: Organic & Biomolecular Chemistry
Malik Aman Ullah, Muhammad Adeel, Muhammad N Tahir, Abdur Rauf, Muhammad Akram, Taibi Ben Hadda, Yahia N Mabkhot, Naveed Muhammad, Fehmida Naseer, Mohammad S Mubarak
Backgorund: The quinoline ring system is one of the most commonly encountered heterocycles in medicinal chemistry, due to the pharmaceutical and medicinal uses of derivatives containing this ring. These quinoline-based compounds have remarkable biological activity, as they are employed as antimalarial, antibacterial, antifungal, and antitumor agents. The quinoline nucleus can be synthesized by various traditional methods such as the Skraup reaction, Friedlaender synthesis, Combes quinoline synthesis, Larock quinoline synthesis, among others...
July 4, 2017: Medicinal Chemistry
Sofia Kiriakidi, Olalla Nieto Faza, Antonios Kolocouris, Carlos Silva López
The formation of chiral heterocycles via cycloisomerization reactions of allene derivatives has gained relevance due to their associated efficiency and atom-economy. The only drawback that keeps these reactions away from being routine synthetic strategies is the control in the regioselectivity (most often 5-endo vs. 6-endo). In this work, we computationally explore the experimental chemistry reported by Krause using N-hydroxy-α-aminoallenes and hydroxylamine ethers as substrates and provide a rationale for the different reactivity observed...
July 19, 2017: Organic & Biomolecular Chemistry
Tomás F Beltrán, Guillermo Zaragoza, Lionel Delaude
The superbulky N-heterocyclic carbenes (NHCs) 2,6-bis(diphenylmethyl)-4-methylimidazol-2-ylidene (IDip*Me) and its 4-methoxy analogue (IDip*OMe) reacted instantaneously with carbon disulfide to afford the corresponding imidazolium-2-dithiocarboxylate zwitterions in high yields. These new dithiolate ligands were fully characterized and their coordination chemistry toward common Re(i) and Ru(ii) metal sources was thoroughly investigated. Neutral [ReBr(CO)3(S2C·NHC)] chelates featured three facially-arranged carbonyl groups on a distorted octahedron, whereas cationic [RuCl(p-cymene)(S2C·NHC)]PF6 complexes displayed a piano-stool geometry...
July 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Özden Karaca, Samuel M Meier-Menches, Angela Casini, Fritz E Kühn
Organometallic compounds currently occupy an important place in the field of medicinal inorganic chemistry due to the unique chemical properties of metal coordination compounds. Particularly, metal compounds ligated by N-heterocyclic carbenes (NHC) have shown high potential for biomedical applications as antimicrobial and anticancer agents during the recent 15 years. Although further studies are necessary to validate the modes of action of this family of compounds, a number of biological targets have been identified, including DNA secondary structures...
June 27, 2017: Chemical Communications: Chem Comm
Tobias Böttcher, Daniel Himmel, Jan Schröder
Herein we present a convenient one-pot route to a sterically demanding superbasic pyridine. Functionalization of the 2,6-positions with the highly sigma-donating boryl-groups shifts the calculated gas phase basicity of the pyridine's nitrogen atom to 1012 kJ mol-1, which outperforms the 'proton sponge' 1,8-bis(dimethylamino)naphthalene (996 kJ mol-1). The diazaboryl groups are oriented orthogonal to the pyridine ring and do not block the N-position, resembling the geometry of commonly used N-heterocyclic carbenes...
June 23, 2017: Chemistry: a European Journal
Yu-Feng Liang, Ning Jiao
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C-H and C-C bond functionalization has proved to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics...
June 21, 2017: Accounts of Chemical Research
Xi Wang, Armido Studer
The chemistry of hypervalent iodine(III) compounds has gained great interest over the past 30 years. Hypervalent iodine(III) compounds show valuable ionic reactivity due to their high electrophilicity but also express radical reactivity as single electron oxidants for carbon and heteroatom radical generation. Looking at ionic chemistry, these iodine(III) reagents can act as electrophiles to efficiently construct C-CF3, X-CF3 (X = heteroatom), C-Rf (Rf = perfluoroalkyl), X-Rf, C-N3, C-CN, S-CN, and C-X bonds...
June 21, 2017: Accounts of Chemical Research
Hidayat Hussain, Ivan R Green
Isocoumarins comprise a six-membered oxygen heterocycle (α-pyranone) along with one aromatic ring and are known to possess interesting biological properties. During the last two decade (1997-2016), isocoumarin chemistry has attracted attention due to its biological and pharmaceutical effects viz., anticancer, anti-diabetic, antibacterial, antimalarial, and fungicidal effects. Areas covered: This review covers the patents on the therapeutic activities of natural and synthetic isocoumarins over the last two decades (1997-2016)...
June 16, 2017: Expert Opinion on Therapeutic Patents
Luis M Martínez-Prieto, Lena Rakers, Angela M López-Vinasco, Israel Cano, Yannick Coppel, Karine Philippot, Frank Glorius, Bruno Chaudret, Piet W N M van Leeuwen
Soluble platinum nanoparticles (Pt NPs) ligated by two different long-chain N-Heterocyclic Carbenes (LC-IPr and LC-IMe) were synthesized and fully characterized by TEM, HRTEM, WAXS, XPS and solution NMR. The surface chemistry of these NPs (Pt@LC-IPr and Pt@LC-IMe) was investigated by FT-IR and solid state NMR using CO as a probe molecule. A clear influence of the bulkiness of the N-substituents was observed on the size, surface state and catalytic activity of these Pt NPs. While Pt@LC-IMe showed no activity in the hydroboration of phenylacetylene, Pt@LC-IPr revealed good selectivity for the trans-isomer which might be supported by a homogeneous species...
June 14, 2017: Chemistry: a European Journal
David E Lewis
Tutor, journalist, patriot, and defector: Aleksei Yevgen'evich Chichibabin made seminal contributions to the chemistry of pyridines. As the Chichibabin reaction enters its second century, it is appropriate to re-examine the life of this remarkable chemist and his legacy to heterocyclic chemistry.
June 12, 2017: Angewandte Chemie
Saurabh Sunil Chitnis, Hazel A Sparkes, Vincent T Annibale, Natalie E Pridmore, Alex M Oliver, Ian Manners
We report the addition of a cyclotriphosphine to a broad range of nitriles giving access to the first examples of free 1-aza-2,3,4-triphospholenes in a rapid, ambient temperature, one-pot, high-yield protocol. The reaction produces electron-rich heterocycles (four lone pairs) and features homoatomic σ-bond heterolysis, thereby combining the key features of the 1,3-dipolar cycloaddition chemistry of azides and cyclopropanes. We also report the first catalytic addition of P-P bonds to the CN triple bond. The coordination chemistry of the new heterocycles is explored...
June 12, 2017: Angewandte Chemie
Bruno Commare, Etienne Schmitt, Fallia Aribi, Armen Panossian, Jean-Pierre Vors, Sergiy Pazenok, Frédéric R Leroux
Fluorinated heterocycles are important building blocks in pharmaceutical, agrochemical and material sciences. Therefore, organofluorine chemistry has witnessed high interest in the development of efficient methods for the introduction of emergent fluorinated substituents (EFS) onto heterocycles. In this context, fluoroalkyl amino reagents (FARs)-a class of chemicals that was slightly forgotten over the last decades-has emerged again recently and proved to be a powerful tool for the introduction of various fluorinated groups onto (hetero)aromatic derivatives...
June 12, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Donglu Xiong, Wenxi Zhou, Zhiwu Lu, Suping Zeng, Jun Joelle Wang
The chromanone scaffold is a privileged structure in heterocyclic chemistry and drug discovery. A highly efficient copper-catalyzed asymmetric conjugated reduction of chromones is developed to give chiral chromanones with good yields (80-99%) and excellent ee values (94->99% ee). Particularly noteworthy is that chiral thiochromanones are also constructed using this method in 74-87% yields with 96-97% ee. The established asymmetric synthesis paves the way for their further pharmaceutical studies.
June 22, 2017: Chemical Communications: Chem Comm
Jie Li, Korkit Korvorapun, Suman De Sarkar, Torben Rogge, David J Burns, Svenja Warratz, Lutz Ackermann
The full control of positional selectivity is of prime importance in C-H activation technology. Chelation assistance served as the stimulus for the development of a plethora of ortho-selective arene functionalizations. In sharp contrast, meta-selective C-H functionalizations continue to be scarce, with all ruthenium-catalysed transformations currently requiring difficult to remove or modify nitrogen-containing heterocycles. Herein, we describe a unifying concept to access a wealth of meta-decorated arenes by a unique arene ligand effect in proximity-induced ruthenium(II) C-H activation catalysis...
June 9, 2017: Nature Communications
Jun Xuan, Armido Studer
Carbo- and heterocycles are widely found in natural products, biologically active structures, medicinally relevant compounds, and in many other fine chemicals. The development of novel, general and efficient methods for their construction has therefore gained great interest in synthetic organic chemistry. Recently, radical chemistry has become a heavily investigated research field (a renaissance!). Along these lines, radical cascade cyclization of 1,n-enynes and diynes has emerged as a powerful strategy for the preparation of carbo- and heterocycles...
July 17, 2017: Chemical Society Reviews
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