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Heterocyclic chemistry

Pravin Patil, Rudrakshula Madhavachary, Katarzyna Kurpiewska, Justyna Kalinowska-Tłuścik, Alexander Dömling
The morpholine and piperazine with their remarkable physical and biochemical properties are popular heterocycles in organic and medicinal chemistry used in rational property design. However, in the majority of cases these rings are added to an existing molecule in a building block approach thus limiting their substitution pattern and diversity. Here we introduce a versatile de novo synthesis of the morpholine and piperazine rings using multicomponent reaction chemistry. The large scale amenable building blocks can be further substituted at up to four positions, making this a very versatile scaffold synthesis strategy...
January 19, 2017: Organic Letters
Tristram Chivers, Risto S Laitinen
Cyclocondensation is a major preparative route for the generation of inorganic heterocycles especially in the case of ring systems involving a Group 15 or 16 element linked to nitrogen. This Perspective will consider recent experimental and computational studies involving the reactions of primary amines (or their synthetic equivalents) with pnictogen and chalcogen halides. The major focus will be a discussion of the identity and role of acyclic intermediates in the reaction pathways to ring formation, as well as the nature of the heterocycles so formed...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Sandra S Eaton, Kirby Huber, Hanan Elajaili, Joseph McPeak, Gareth R Eaton, Lauren E Longobardi, Douglas W Stephan
Preparation of the stable boron-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), by frustrated Lewis pair chemistry has been reported recently. Electron paramagnetic resonance measurements of this radical were made at X-band in toluene:dichloromethane (9:1) from 10 to 293K, in toluene from 180 to 293K and at Q-band at 80K. In well-deoxygenated 0.1mM toluene solution at room temperature hyperfine splittings from (11)B, four pairs of (1)H, and 5 pairs of (19)F contribute to an EPR spectrum with many resolved lines...
December 30, 2016: Journal of Magnetic Resonance
Anindya K Swarnakar, Michael J Ferguson, Robert McDonald, Eric Rivard
Despite recent advances in main group N-heterocyclic carbene (NHC) coordination chemistry, gallium hydrides remain, in large part, an unexplored area of research. In this paper we outline efficient routes to azide- and amido-functionalized gallium hydrides such as NHC·GaH2N3 and NHC·GaH2N(SiMe3)2 and explore these species as potential precursors to HGaNH complexes and bulk gallium nitride (GaN).
January 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Cameron M E Graham, Taylor E Pritchard, Paul D Boyle, Juuso Valjus, Heikki M Tuononen, Paul J Ragogna
Four-membered rings with a P2 Ch2 core (Ch=S, Se) and phosphorus in the +3 oxidation state have been synthesized. The utility of these rings as a source of monomeric phosphinidene chalcogenides was probed by the addition of an N-heterocyclic carbene, resulting in a base-stabilized phosphinidene sulfide. Similarly, persistence of the phosphinidene selenide in solution was shown through cycloaddition chemistry with 2,3-dimethylbutadiene at elevated temperatures. The observed reactivity was explained by detailed computational work that established the conditions upon which the P2 Ch2 rings can liberate phosphinidene chalcogenides...
January 10, 2017: Angewandte Chemie
Mohammed I El-Gamal, Hanan S Anbar
Several pyrrolopyridines or azaindoles have been reported in the literature as biologically-active molecules. Most of them are anticancer agents, and few possess other therapeutic effects. Areas covered: The most recent biologically-active pyrrolopyridine derivatives have been reviewed from the patents and research articles published from 2010 to the mid of 2016. Their structural and biological features have been explained. In general, the pyrrolopyridine scaffold mimics the purine ring of the ATP molecule...
January 9, 2017: Expert Opinion on Therapeutic Patents
Samuel de Visser, Fabian Cantu Reinhard
N-heterocyclic carbenes (NHC) are common catalyst features in transition metal chemistry. Recently, a cyclic system containing four NHC groups with a central iron atom was synthesized and its iron(IV)-oxo characterized, [FeIV(O)(cNHC4)]2+. This tetra-cyclic NHC ligand system may give the iron(IV)-oxo species unique catalytic properties as compared to traditional nonheme iron and heme iron ligand systems. Therefore, we performed a computational study on the structure and reactivity of the [FeIV(O)(cNHC4)]2+ complex in substrate hydroxylation and epoxidation reactions...
January 4, 2017: Chemistry: a European Journal
Robert H Crabtree
The different types of acceptorless alcohol dehydrogenation (AAD) reactions are discussed, followed by the catalysts and mechanisms involved. Special emphasis is put on the common appearance in AAD of pincer ligands, of noninnocent ligands, and of outer sphere mechanisms. Early work emphasized precious metals, mainly Ru and Ir, but interest in nonprecious metal AAD catalysis is growing. Alcohol-amine combinations are discussed to the extent that net oxidation occurs by loss of H2. These reactions are of potential synthetic interest because they can lead to N heterocycles such as pyrroles and pyridines...
January 4, 2017: Chemical Reviews
Bohdan Ardan, Vasyl Kinzhybalo, Yurii Slyvka, Olga Shyyka, Mykhaylo Luk Yanov, Tadeusz Lis, Marian Mys Kiv
As an important class of heterocyclic compounds, 1,3,4-thiadiazoles have a broad range of potential applications in medicine, agriculture and materials chemistry, and were found to be excellent precursors for the crystal engineering of organometallic materials. The coordinating behaviour of allyl derivatives of 1,3,4-thiadiazoles with respect to transition metal ions has been little studied. Five new crystalline copper(I) π-complexes have been obtained by means of an alternating current electrochemical technique and have been characterized by single-crystal X-ray diffraction and IR spectroscopy...
January 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
Tamal Chatterjee, A Srinivasan, Mangalampalli Ravikanth, Tavarakere K Chandrashekar
Porphyrins and expanded porphyrins have attracted the attention of chemists for a long time in view of their diverse applications in catalysis; as anion, cation, and neutral substrate receptors; as ligands to coordinate large metal ions; as nonlinear optical materials, MRI contrasting agents, and sensitizers for photodynamic therapy (PDT); and more recently as models for aromaticity (both Hückel and Möbius). A diverse range of synthetic expanded porphyrins containing up to 96π electrons have been reported, and their properties have been exploited for various applications...
December 29, 2016: Chemical Reviews
Lucía Álvarez-Rodríguez, Javier Brugos, Javier A Cabeza, Pablo García-Álvarez, Enrique Pérez-Carreño, Diego Polo
A PGeP pincer-type germylene, Ge(NCH2P(t)Bu2)2C6H4, which contains two phosphane groups hanging from the N atoms of an N-heterocyclic germylene fragment, has been isolated for the first time. This compound has already furnished a rich transition metal derivative chemistry (Co, Rh, and Pd) that includes complexes containing bridging P,Ge,P-, chelating P,Ge- and pincer P,Ge,P-ligands.
December 23, 2016: Chemical Communications: Chem Comm
Fangyong Yan, Nilesh R Dhumal, Hyung J Kim
Ionic liquids (ILs) provide a promising medium for CO2 capture. Recently, the family of ILs comprising imidazolium-based cations and acetate anions, such as 1-ethyl-3-methylimidazolium acetate (EMI(+)OAc(-)), has been found to react with CO2 and form carboxylate compounds. N-Heterocyclic carbene (NHC) is widely assumed to be responsible by directly reacting with CO2 though NHC has not been detected in these ILs. Herein, a computational analysis of CO2 capture in EMI(+)OAc(-) is presented. Quantum chemistry calculations predict that NHC is unstable in a polar environment, suggesting that NHC is not formed in EMI(+)OAc(-)...
January 4, 2017: Physical Chemistry Chemical Physics: PCCP
Adam Gorczyński, Jack M Harrowfield, Violetta Patroniak, Artur R Stefankiewicz
Quaterpyridine (qtpy) ligands have found significant applications as N-heterocyclic scaffolds in self-assembly processes, in particular the formation of various metallosupramolecular architectures, limited, however, by difficulties in their synthesis. Recent progress in the preparative organic and organometallic chemistry of polypyridines has resulted in the elimination of the most serious drawbacks concerning qtpy synthesis, consequently giving rise to a renewed interest in this class of compounds. Herein, we endeavor to define the essential aspects of quaterpyridine chemistry and provide the reader with a perspective on the ways in which this field has begun to flourish...
December 14, 2016: Chemical Reviews
Wasim Akhtar, Mohemmed Faraz Khan, Garima Verma, M Shaquiquzzaman, M A Rizvi, Syed Hassan Mehdi, Mymoona Akhter, M Mumtaz Alam
Benzimidazole, a fused heterocycle bearing benzene and imidazole 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. This nitrogen containing heterocycle is a part of a number of therapeutically used agents. Moreover, a number of patents concerning this moiety in the last few years further highlight its worth. The present review covers the recent work published by scientists across the globe during last five years...
December 5, 2016: European Journal of Medicinal Chemistry
Demian Marchione, Maria Izquierdo, Giovanni Bistoni, Remco W A Havenith, Alceo Macchioni, Daniele Zuccaccia, Francesco Tarantelli, Leonardo Belpassi
The Dewar-Chatt-Duncanson (DCD) model provides a successful theoretical framework to describe the nature of the chemical bond in transition metal compounds and is especially useful in structural chemistry and catalysis. However, how to actually measure its constituents (substrate to metal donation and metal to substrate back-donation) is yet uncertain. Recently, we demonstrated that the DCD components can be neatly disentangled and the π back-donation component put in strict correlation with some experimental observables...
December 10, 2016: Chemistry: a European Journal
Alpana K Gupta, Mausumi Bharadwaj, Anoop Kumar, Ravi Mehrotra
As a result of the toxicity of currently available anticancer drugs and the inefficiency of chemotherapeutic treatments, the design and discovery of effective and selective antitumor agents continues to be a hot topic in organic medicinal chemistry. Targeted therapy is a newer type of cancer treatment that uses drugs designed to interfere with specific molecules necessary for tumor growth and progression. This review explains the mechanism of regulation of p53 (tumor suppressor protein) by MDM2 and illustrates the role of targeting p53-MDM2 protein-protein interaction using small molecules as a new cancer therapeutic strategy...
February 2017: Topics in Current Chemistry (Journal)
Ana B Fraga-Timiraos, Gemma M Rodríguez-Muñiz, Vicente Peiro-Penalba, Miguel A Miranda, Virginie Lhiaubet-Vallet
Electron transfer involving nucleic acids and their derivatives is an important field in bioorganic chemistry, specifically in connection with its role in the photo-driven DNA damage and repair. Four-membered ring heterocyclic oxetanes and azetidines have been claimed to be the intermediates involved in the repair of DNA (6-4) photoproduct by photolyase. In this context, we examine here the redox properties of the two azetidine isomers obtained from photocycloaddition between 6-aza-1,3-dimethyluracil and cyclohexene...
December 7, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Imants Kreituss, Jeffrey W Bode
The preparation of enantioenriched chiral compounds by kinetic resolution dates back to the laboratories of Louis Pasteur in the middle of the 19th century. Unlike asymmetric synthesis, this process can always deliver enantiopure material (ee > 99%) if the reactions are allowed to proceed to sufficient conversion and the selectivity of the process is not unity (s > 1). One of the most appealing and practical variants is acylative kinetic resolution, which affords easily separable reaction products, and several highly efficient enzymatic and small molecule catalysts are available...
December 20, 2016: Accounts of Chemical Research
Dokyoung Kim, Jonathan M Zuidema, Jinyoung Kang, Youlin Pan, Lianbin Wu, David Warther, Barry Arkles, Michael J Sailor
Heterocyclic silanes containing Si-N or Si-S bonds in the ring undergo a ring opening reaction with -OH groups at the surface of porous Si nanostructures to generate -SH or -NH functional surfaces, grafted via O-Si bonds. The reaction is substantially faster (0.5-2 h at 25 °C) and more efficient than hydrolytic condensation of trialkoxysilanes on similar hydroxy-terminated surfaces, and the reaction retains the open pore structure and photoluminescence of the quantum-confined silicon nanostructures. The chemistry is sufficiently mild to allow trapping of the test protein lysozyme, which retains its enzymatic activity upon release from the modified porous nanostructure...
November 23, 2016: Journal of the American Chemical Society
Mehdi Bayat, Asieh Sedghi, Leila Ebrahimkhani, Seyyed Javad Sabounchei
N-Heterocyclic carbene and phosphorus ylides are inorganic and organometallic ligands, and their coordination chemistry with transition elements, particularly group 11 metals, would be noticeable. This study seeks to characterize the structure and nature of the C→M bond of group 11 metals (M = Cu(i), Ag(i), Au(i)) in coordination with different monodentate phosphorus ylides {P(Ph)3CHR} and N-heterocyclic carbenes (NHC(R)) (where R = F, Cl, Br, CF3, CH3, H, C(CH3)3, Si(CH3)3, SiH3, Ph). In this regard, DFT calculations with the PBE/def2-TZVP level of theory were applied...
December 20, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
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