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Heterocyclic chemistry

Shalki Choudhary, Pankaj Kumar Singh, Om Silakari
Nitrogen and sulphur based heterocyclic molecules have gained significant attention owing to their broad spectrum pharmacological profiles. Thiazine is one of such promising scaffolds which has been widely utilized in the synthesis of compounds that possess interesting biological profile including anti-proliferative, anti-bacterial, antipsychotic, analgesic, anti-inflammatory, antifungal and antiviral activities. The current review focus on the chemistry of thiazine and its derivatives along with potential pharmacological activities reported for them in scientific literature...
April 16, 2018: Mini Reviews in Medicinal Chemistry
Guilherme Felipe Dos Santos Fernandes, Aline Renata Pavan, Jean Leandro Dos Santos
Heterocyclic N-oxides have emerged as promising agents against a number of diseases and disorders, especially infectious diseases. This review analyzes the emergence and development of this scaffold in the medicinal chemistry, focusing mainly on the discovery of new heterocyclic N-oxide compounds with potent activity against tuberculosis, malaria and neglected tropical diseases (i.e. leishmaniasis and Chagas disease). A number of heterocyclic N-oxide are described herein, nevertheless, the following chemical classes deserve to be highlighted due to the large number of reports in the literature about their promising pharmacological effects: furoxan, benzofuroxan, quinoxaline 1,4-di-N-oxide, indolone N-oxide and benzimidazole N-oxide...
April 17, 2018: Current Pharmaceutical Design
V Alagarsamy, K Chitra, G Saravanan, V Raja Solomon, M T Sulthana, B Narendhar
Most of the drugs and pharmacologically relevant molecules possess heterocyclic ring structures and presence of hetero atoms or groupings divulges privileged specificities in their pharmacological targets. Especially the heterocyclic systems, quinazoline is a biologically imperative scaffold known to be linked with several pharmacological activities. Some of the protuberant pharmacological responses attributed to this system are analgesic, anti-inflammatory, anti-convulsant, sedative-hypnotic, anti-histaminic, anti-hypertensive, anti-cancer, anti-microbial, anti-tubercular and anti-viral activities...
March 30, 2018: European Journal of Medicinal Chemistry
Xiaodong Tang, Wanqing Wu, Wei Zeng, Huanfeng Jiang
Selective oxidation, a fundamental organic transformation of critical importance, produces value-added products from simple organic molecules. This process is extensively used to incorporate heteroatoms into carbon-based molecules, where high-valent metal salts, hypervalent halogen reagents, and peroxides are widely used as oxidants. Oxidation reactions are extremely challenging because their selectivity is hard to control and/or they form significant quantities of unwanted waste derived from the stoichiometric oxidants...
April 12, 2018: Accounts of Chemical Research
Syeda M Hussain, Valdo Rodrigues Herling, Paulo Henrique Mazza Rodrigues, Ishrat Naz, Hamayun Khan, Muhammad Tahir Khan
Photosensitization is severe dermatitis or oxidative/chemical changes in the epidermal tissues activated by the light-induced excitation of molecules within the tissue. It is a series of reactions mediated through light receptors and is more common when the plant-produced metabolites are heterocyclic/polyphenols in nature. The areas affected are exposed body parts and mostly non-pigmented areas with least ultraviolet protection. Similarly, cellular alteration also occurs in the affected animal's dermal tissues and body parts and grazing animals by the accumulation and activation of photodynamic molecules...
April 6, 2018: Tropical Animal Health and Production
Muhammad Arif Kassim, Ubaidullah H M Yassin, Ai Ling Tan, Anwar Usman, Malai Haniti S A Hamid
Hydrazones and their derivatives are closely related to imine compounds and are potential antimicrobial agents. They have also found application in supramolecular chemistry as multitopic ligands to link multiple metal centres for the design of hybrid molecular frameworks. The molecule of the title compound, C6 H8 N4 , consists of an imine linkage with an N-N bond length of 1.3540 (14) Å. This asymmetric compound is nearly planar and adopts an E configuration about the azomethine C=N double bond. In the solid state, there are two intermolecular N-H...
April 1, 2018: Acta Crystallographica. Section C, Structural Chemistry
Xiaowei Wu, Haitao Ji
The development of an efficient approach to construct fused polycyclic systems bearing a quaternary carbon center represents a great challenge to synthetic chemistry. Herein, we report a Rh(III)-catalyzed [4 + 1] annulation of propargyl alcohols with various heterocyclic scaffolds under air atmosphere. Diverse fused heterocycles containing a quaternary carbon center were obtained in moderate to good yields. Additionally, this method features high atom-economy, metal oxidant free, simple operation, and compatibility with various functional groups...
April 2, 2018: Journal of Organic Chemistry
Pankaj Kumar Singh, Om Silakari
O-heterocycles have been explored since long in the field of medicinal chemistry but they have not yet been given their due significance and are usually shunned out in comparison to N-heterocycles. Designing of bioactive molecules for almost every pathophysiological condition is primarily focused on designing novel N-heterocycles. The basic reasons for this bias are the ease of synthesis and possible mimicking of physiological molecules by N-heterocycles. But considering only this criteria never provides any breakthrough molecule for any disease condition, rather risk of toxicity/side effects are increased with such molecules...
March 30, 2018: ChemMedChem
Nikolai E Skoblikow, Andrei A Zimin
The hypothesis of hot volcanic organic stream as the most probable and geologically plausible environment for abiogenic polycondensation is proposed. The primary synthesis of organic compounds is considered as result of an explosive volcanic (perhaps, meteorite-induced) eruption. The eruption was accompanied by a shock wave propagating in the primeval atmosphere and resulting in the formation of hot cloud of simple organic compounds-aldehydes, alcohols, amines, amino alcohols, nitriles, and amino acids-products, which are usually obtained under the artificial conditions in the spark-discharge experiments...
March 28, 2018: Journal of Molecular Evolution
Lucien D Caspers, Boris J Nachtsheim
C-C triple bonds are amongst the most versatile functional groups in synthetic chemistry. Complementary to the Sonogashira coupling the direct metal-catalyzed alkynylation of C-H bonds has emerged as a highly promising approach in recent years. To guarantee a high regioselectivity suitable directing groups (DGs) are necessary to guide the transition metal (TM) into the right place. In this Focus Review we present the current developments in DG-mediated C(sp²)-H and C(sp3)-H modifications with terminal alkynes under oxidative conditions and with electrophilic alkynylation reagents...
March 25, 2018: Chemistry, An Asian Journal
Evgeny Putin, Arip Asadulaev, Quentin Vanhaelen, Yan Ivanenkov, Anastasiya Aladinskaya, Alex Aliper, Alex Zhavoronkov
In this paper, we propose the deep neural network Adversarial Threshold Neural Computer (ATNC). The ATNC model is intended for the de novo design of novel small-molecule organic structures. The model is based on generative adversarial net- work architecture and reinforcement learning. ATNC uses a Differentiable Neural Com- puter as a generator and has a new specific block, called adversarial threshold (AT). AT acts as a filter between the agent (generator) and the environment (discriminator + objective reward functions)...
March 23, 2018: Molecular Pharmaceutics
G Malik, R A Swyka, V K Tiwari, X Fei, G A Applegate, D B Berkowitz
Herein we describe a formal thiocyanopalladation/carbocyclization transformation and its parametrization and optimization using a new elevated temperature plate-based version of our visual colorimetric enzymatic screening method for reaction discovery. The carbocyclization step leads to C-SCN bond formation in tandem with C-C bond construction and is highly stereoselective, showing nearly absolute 1,2- anti -stereoinduction (5 examples) for substrates bearing allylic substitution, and nearly absolute 1,3- syn -stereoinduction (16 examples) for substrates bearing propargylic substitution...
December 1, 2017: Chemical Science
David C Blakemore, Luis Castro, Ian Churcher, David C Rees, Andrew W Thomas, David M Wilson, Anthony Wood
Despite decades of ground-breaking research in academia, organic synthesis is still a rate-limiting factor in drug-discovery projects. Here we present some current challenges in synthetic organic chemistry from the perspective of the pharmaceutical industry and highlight problematic steps that, if overcome, would find extensive application in the discovery of transformational medicines. Significant synthesis challenges arise from the fact that drug molecules typically contain amines and N-heterocycles, as well as unprotected polar groups...
April 2018: Nature Chemistry
Mayura Kale, Gajanan Sonwane, Rajesh Nawale, Vishnukant Mourya
There has been a rapid surge in the research and exchange of ideas in various areas of chemistry such as organic, pharmaceutical, analytical, and medicinal chemistry. It is well recognized that heterocycles are vital components of many biochemical processes. Pharma industry comprises of more than 75% of top selling drugs that are of heterocyclic origin. Among many diseases, cancer can be considered to be a dreaded disease that has overtaken the masses across the globe. Hence, there has been a need to develop drugs that are less toxic and do not provide resistance in the long run...
March 20, 2018: Current Computer-aided Drug Design
Çinel Köksal Karayildirim, Mustafa Kotmakçi, Erkan Halay, Kadir Ay, Yücel Başpinar
5-Fluorouracil is one of the first line drugs for the systemic therapy of solid tumors like breast, colorectal, oesophageal, stomach, pancreatic, head and neck. It could be shown that sugars can improve the absorption across cell membranes and can help to bypass some pharmacokinetic problems. Carbohydrates as most common organic molecules are an important issue of plant and animal metabolisms. They are non toxic and have important duties in the body like participating in DNA and RNA synthesis and being responsible for energy production...
March 2018: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
Pengfei Zhang, Yu Zhou, Xu Han, Jinyi Xu, Hong Liu
The dearomatizing annulation reaction is a significant challenge in organic chemistry. The direct activation of α-carbons of simple saturated esters, as nucleophiles, is an important synthesis strategy. In the present study, we disclose [3+2] dearomatizing annulation reactions with direct activating α-carbons of saturated carboxylic esters and N-iminoisoquinolinium ylides, which possess highly enantioselective characteristics, catalyzed by N-heterocyclic carbenes (NHCs). The protocol achieves isoquinoline dearomatization and the construction of tricyclic chiral products under mild conditions with good yield, substrate tolerance, diastereoselectivity, and excellent enantioselectivity...
March 16, 2018: Journal of Organic Chemistry
Pramod Singh Negi, Jitendra Singh, Geeta Joshi Nee Pant, Msm Rawat
Nitrogen containing five membered heterocyclics play vital role in pharmaceuticals as well as medicinal chemistry. Pyrazolines play a significant role among other heterocycles because of their therapeutic and pharmacological properties. 2-Pyrazolines displayed a wide variety of biological activities such as anticancer, antiepileptic, anti-aids, antimalarial, insecticidal and antitubercular etc. and they are used as pesticides, herbicides, fungicides and also used in agrochemical research and analytical chemistry...
March 13, 2018: Anti-cancer Agents in Medicinal Chemistry
Mohammed Benadallah, Oualid Talhi, Fatiha Nouali, Nourredine Choukchou-Braham, Khaldoun Bachari, Artur M S Silva
The present review deals with the progress in medicinal chemistry of spirocyclic compounds, a wider class of natural and synthetic organic molecules, defined as a hybrid of two molecular entities covalently linked via a unique tetrahedral carbon. This spiro central carbon confers to the molecules a tridimensional structurally oriented framework, which is found in many medicinally relevant compounds, a well-known example is the anti-hypertensive spironolactone. Various bioactive natural products possess the privileged spiro linkage and different chemo-types thereof become synthetically accessible since the 20th century...
March 9, 2018: Current Medicinal Chemistry
Snehali Mali, Sachin Shinde, Shashikant Damte, Suresh Patil
Without using any toxic or hazardous reagent, ligand, acid, transition metal catalyst, additives/promoters and organic solvent, green Knoevenagel condensation and tandem Knoevenagel-Michael reactions have been successfully carried out by using chickpea leaf exudates as a naturally sourced Bronsted acid type bio-catalyst. The reaction proceeds in neat chickpea leaf exudates at room temperature in aqueous conditions in very short reaction times, and therefore, it is an evergreen and environmentally sound alternative to the existing protocols for benzopyran synthesis...
February 2018: Royal Society Open Science
Han Miao, Johannes Schmidt, Tobias Heil, Markus Antonietti, Marc Willinger, Ryan Guterman
Imidazolium-based ionic liquids have the ability to undergo a variety of chemical reactions through an N-heterocyclic carbene (NHC) intermediate, which has expanded the chemical toolbox for new applications. Despite their uses and exploration, the carbene-forming properties and applications of their polymeric congeners, poly(ionic liquid)s (PILs), is still underdeveloped. In this work we explore the NHC-forming properties of a theophylline-derived PIL for nanogel synthesis. Using silver oxide as both the carbene forming reagent and crosslinker, nanogels containing individually stabilized ions can be created with different sizes and morphology, including large "galaxy-like" superstructures...
March 6, 2018: Chemistry: a European Journal
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