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Heterocyclic chemistry

Paul Mehlmann, Christian Mück-Lichtenfeld, Tristan T Y Tan, Fabian Dielmann
We report the synthesis and remarkable properties of phosphine P(NIiPr)3 (NIiPr = 1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidenamino), a crystalline solid accessible through a short and scalable route. Evaluation of the electron donor properties reveals a TEP value of 2029.7 cm-1 for the new phosphine that is significantly lower than those of all known phosphines or even N-heterocyclic carbenes. Moreover, P(NIiPr)3 is more basic [pKBH+(MeCN) = 38.8] than Verkade's proazaphosphatranes, thus being the strongest reported nonionic phosphorus(III) superbase...
October 25, 2016: Chemistry: a European Journal
Abdul Hameed, Mariya Al-Rashida, Maliha Uroos, Syed Ali, Khalid M Khan
Schiff bases are synthetically accessible and structurally diverse compounds, typically obtained by facile condensation between an aldehyde, or a ketone with primary amines. Schiff bases contain an azomethine (-C=N-) linkage that stitches together two or more biologically active aromatic/heterocyclic scaffolds to form various molecular hybrids with interesting biological properties. Schiff bases are versatile metal complexing agents and have been known to coordinate all metals to form stable metal complexes with vast therapeutic applications...
October 24, 2016: Expert Opinion on Therapeutic Patents
Bubun Banerjee
Heterocycles are the backbone of organic compounds. Specially, N- &O-containing heterocycles represent privileged structural subunits well distributed in naturally occurring compounds with immense biological activities. Multicomponent reactions (MCRs) are becoming valuable tool for synthesizing structurally diverse molecular entities. On the other hand, the last decade has seen a tremendous outburst in modifying chemical processes to make them sustainable for the betterment of our environment. The application of ultrasound in organic synthesis is fulfilling some of the goals of 'green and sustainable chemistry' as it has some advantages over the traditional thermal methods in terms of reaction rates, yields, purity of the products, product selectivity, etc...
October 14, 2016: Ultrasonics Sonochemistry
Song-Lin Zhang, Ze-Long Yu
Divergent synthesis of indoles, oxindoles, isocoumarins and isoquinolinones is described in this report by using a general Pd-catalyzed tandem reaction of β-hydroxy carbonyl compounds with aryl halides bearing an ortho-nitro, -ester or -cyano substituent. A key retro-aldol/α-arylation reaction is involved that merges classic Pd cross-coupling chemistry with novel Pd-promoted retro-aldol C-C activation to produce α-arylated ketones or esters. Subsequent intramolecular condensation of the carbonyl with the ortho-synthon gives target heterocycles...
October 21, 2016: Organic & Biomolecular Chemistry
Sudipta Saha, Vinit Raj, Amit Rai
The chemistry of heterocyclic containing, 1,3,4-thiadiazole has been an interesting field of study from ancient years. Subsequently, 1,3,4-thiadiazole nucleus constitutes a significant class of compounds for new drug development. Recently, various 1,3,4-thiadiazole derivatives have been synthesized and evaluated their biological activities including antimicrobial, antituberculosis, antioxidant, anti-inflammatory, anticonvulsants, antidepressant and anxiolytic, antihypertensive, anticancer and antifungal activity...
October 13, 2016: Anti-cancer Agents in Medicinal Chemistry
Pierre Regenass, Stéphanie Riché, Florent Péron, Didier Rognan, Marcel Hibert, Nicolas Girard, Dominique Bonnet
A rapid and atom economical multicomponent synthesis of complex aza-diketopiperazines (aza-DKPs) driven by Rh(i)-catalyzed hydroformylation of alkenylsemicarbazides is described. Combined with catalytic amounts of acid and the presence of nucleophilic species, this unprecedented multicomponent reaction (MCR) enabled the formation of six bonds and a controlled stereocenter from simple substrates. The efficacy of the strategy was demonstrated with a series of various allyl-substituted semicarbazides and nucleophiles leading to the preparation of 3D-shaped bicyclic aza-DKPs...
September 21, 2016: Organic & Biomolecular Chemistry
Sonu Kumar, Rakesh K Saunthwal, Trapti Aggarwal, Siva K Reddy Kotla, Akhilesh K Verma
An efficient step-economical tandem approach for the direct synthesis of pyrido fused indole, quinoline, benzofuran and benzothiophene derivatives using a bimetallic Pd/Cu catalytic system has been described. The three component reaction of o-halo aldehydes, alkynes and tert-butylamine leads to the synthesis of biologically active polyheterocycles. The present strategy involves the dual role of tert-butylamine and copper(i) in Sonogashira coupling followed by electrophilic cyclization through imine formation...
September 26, 2016: Organic & Biomolecular Chemistry
Fei Pan, Chao Shu, Long-Wu Ye
N-Containing tricyclic compounds, especially the tricyclic N-heterocycles, are important structural motifs that possess significant potential in organic chemistry for their momentous applications in natural and man-made bioactive molecules. Gold catalysis, which exhibits specific catalytic properties in terms of both high reactivity and selectivity for various organic transformations, has proven to be a powerful tool for the straightforward synthesis of cyclic compounds, especially the polycyclic molecules...
October 12, 2016: Organic & Biomolecular Chemistry
Kishor S Jain
No abstract text is available yet for this article.
2016: Current Topics in Medicinal Chemistry
Jean-François Lefebvre, Dounia Saadallah, Philipp Traber, Stephan Kupfer, Stefanie Gräfe, Benjamin Dietzek, Isabelle Baussanne, Julien De Winter, Pascal Gerbaux, Cécile Moucheron, Murielle Chavarot-Kerlidou, Martine Demeunynck
The preparation and characterization of three series of novel ruthenium(ii) complexes are reported, each series differing by the nature of the ancillary ligands (2,2'-bipyridine - bpy, 1,10-phenanthroline - phen or 1,4,5,8-tetraazaphenanthrene - TAP). The third ligand was either the heptacyclic heterocycle dipyrido[3,2-a:2',3'-c]quinolino[3,2-h]phenazine (dpqp) substituted at position 12 by an hydroxyl (oxo), 2,2-dimethoxyethylamine (DMEA) or halogeno (Cl or Br) substituent, or the octacyclic dipyrido[3,2-a:2',3'-c]pyrido[2,3,4-de]quinolino[3,2-h]phenazine (dppqp), prepared by a multi-step "chemistry on the complex" strategy from [RuL2(oxo-dpqp)](PF6)2...
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Annika Gackstatter, Holger Braunschweig, Thomas Kupfer, Christian Voigt, Nicole Arnold
Reaction of a N-heterocyclic silylene (NHSi) with PhBX2 (X=Cl, Br) readily afforded six-membered silaborinines through an insertion/ring expansion sequence. Increasing the sterics of the borane from phenyl to duryl enabled the selective generation and isolation of the highly colored silylborane intermediates. Theoretical studies on the mechanism and energetics of the silaborinine formation were fully consistent with the experimental observations.
October 6, 2016: Chemistry: a European Journal
Biswadip Banerji, K Chandrasekhar, Sunil Kumar Killi, Sumit Kumar Pramanik, Pal Uttam, Sudeshna Sen, Nakul Chandra Maiti
'Click reactions' are the copper catalysed dipolar cycloaddition reaction of azides and alkynes to incorporate nitrogens into a cyclic hydrocarbon scaffold forming a triazole ring. Owing to its efficiency and versatility, this reaction and the products, triazole-containing heterocycles, have immense importance in medicinal chemistry. Copper is the only known catalyst to carry out this reaction, the mechanism of which remains unclear. We report here that the 'click reactions' can also be catalysed by silver halides in non-aqueous medium...
September 2016: Royal Society Open Science
Jiachun Liu, Yan-Ling Wu, Huri Piao, Xiaoyin Zhao, Wen Zhang, Yanli Wang, Minrui Liu
At present, diseases resulting from various reasons have been causing deadly fears to humans and previously incogitable losses to health. Meanwhile, the patient compliance has been weakening because of drug resistance and serious drug adverse effects. There is therefore an urgent need for the development of novel structural agents. Rhodanine derivatives have represented wide biological activities, as well as significant industrial applications, which suggests that rhodanine heterocycle represents a key structural motif in heterocyclic chemistry and occupies a prominent position in drug discovery...
September 28, 2016: Mini Reviews in Medicinal Chemistry
Zhenda Tan, He Zhao, Changjian Zhou, Huanfeng Jiang, Min Zhang
A new aerobic copper-catalyzed halocyclization reaction of methyl-N-heteroaromatics and aliphatic amines has been developed, which enables straightforward access to functionalized imidazo-fused N-heterocycles with the merits of good functional tolerance, use of easily-available copper salts as the catalysts, lithium halides as the halogen sources and O2 as a sole oxidant. Owing to the reaction features selective introduction of halogen functionalities to the newly formed imidazo-ring, further extensions of the developed chemistry towards synthetic diversity, including effective access to functional materials, are easily envisioned...
October 3, 2016: Journal of Organic Chemistry
Chiara Cabrele, Oliver Reiser
The synthesis of heterocycles is arguably one of the oldest and at the same time one of the youngest disciplines of organic chemistry. Groundbreaking principles to form heterocycles, mainly by condensation reactions, were recognized in the beginning of the 19th century, and many of the classical reactions discovered at that time are still of great value today. In the 21st century, the wealth of synthetic methodology toward heterocycles is overwhelming, and catalysis, in particular, as one of the cornerstones of green and sustainable chemistry has contributed in a major way to these developments...
October 10, 2016: Journal of Organic Chemistry
Maribel Portillo, Michael A Maxwell, James H Frederich
A photochemical method for the direct synthesis of 1H-pyrazoles from pyridazine N-oxides was developed. This chemistry features a regioselective approach to nonsymmetrically substituted pyridazine N-oxides. Herein, we highlight the first strategic use of photoinduced ring-opening reactions of 1,2-diazine N-oxides for the preparative synthesis of nitrogen heterocycles.
October 7, 2016: Organic Letters
Ahmad Sami Shawali
This review covers a summary of the literature data published on the chemistry of bis-hydrazonoyl halides over the last four decades. The biological activities of some of the bis-heterocyclic compounds obtained from these bis-hydrazonoyl halides are also reviewed and discussed.
November 2016: Journal of Advanced Research
Eduardo Sobarzo-Sánchez
No abstract text is available yet for this article.
September 6, 2016: Current Topics in Medicinal Chemistry
Neetipalli Thrimurtulu, Arnab Dey, Debabrata Maiti, Chandra M R Volla
The reactivity of allenes in transition-metal-catalyzed C-H activation chemistry is governed by the formation of either alkenyl-metal (M-alkenyl) or metal-π-allyl intermediates. Although either protonation or a β-hydride elimination is feasible with a M-alkenyl intermediate, cyclization has remained unexplored to date. Furthermore, due to the increased steric hindrance, the regioselectivity for the intramolecular cyclization of the metal-π-allyl intermediate was hampered towards the more substituted side...
September 26, 2016: Angewandte Chemie
Sachin Suresh Bhojgude, Anup Bhunia, Akkattu T Biju
Arynes are highly reactive intermediates having several applications in organic synthesis for the construction of various ortho-disubstituted arenes. Traditionally, arynes are generated in solution from haloarenes under strongly basic conditions. However, the scopes of many of the aryne reactions are limited because of the harsh conditions used for their generation. The renaissance of interest in aryne chemistry is mainly due to the mild conditions for their generation by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates...
September 20, 2016: Accounts of Chemical Research
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