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Cembrane Diterpenes: Chemistry and Biological Properties
Bin Yang, Xue-Feng Zhou, Xiu-Ping Lin, Juan Liu, Yan Peng, Xian-Wen Yang and Yonghong Liu
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00151]
Regioselectivity of the Liquid-phase Mononitration of Weakly Activated Arenes over Cross-linked Clays
Xinhua Peng, Xiongzi Dong and Yanfang Tai
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00152]
5-Aminouracil as Effective Inhibitor of Peroxyl Radicals: Experimental and Theoretical Studies
Stanislav A. Grabovskiy, Irina G. Konkina, Yuri I. Murinov and Natalia N. Kabal’nova
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00153]
Preparation and Evaluation of Lysozyme Molecularly Imprinted Polymer Film on the Surface of Multi-wall Carbon Nanotubes
Guozhen Fang, Xiaorui Zhai, Qiliang Deng, Shifang Yuan, Meirong Cao and Shuo Wang
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00154]
Regio- and Stereoselectivity of the 1,3-dipolar Cycloaddition of Pyridinium-3-olates and Pyrazinium-3-olates with Methyl Methacrylate: A Density Functional Theory Exploration
Lydia Rhyman, Hassan H. Abdallah, Sabina Jhaumeer-Laulloo, Luis R. Domingo, John A. Joule and Ponnadurai Ramasami
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00155]
Immobilized Ionic Liquids in Organic Chemistry
Manuela A. Pereira
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00156]
Nucleophilic Participation in the Solvolyses of (Arylthio)methyl Chlorides and Derivatives: Application of Simple and Extended Forms of the Grunwald-Winstein Equations
Dennis N. Kevill, Young Hoon Park, Byoung-Chun Park and Malcolm J. D’Souza
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00157]
Conjugated Polyelectrolytes: Synthesis and Application in Biomolecule Detection
Lingyun Wang, Huihui Li and Derong Cao
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00158]
Electroluminescent and Photovoltaic Properties of Silole-Based Materials
Huiying Fu and Yuanrong Cheng
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00159]
Applications of the in situ Propargyl-Allenyl Isomerization in Organic Synthesis
Yanpeng Xing, Yuxiu Wei and Hongwei Zhou
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00160]
Stereoselective Biotransformations as an Effective Tool for the Synthesis of Chiral Compounds with P-C Bond – Scope and Limitations of the Methods
Ewa Żymańczyk-Duda and Magdalena Klimek-Ochab
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00161]
Synthesis of Celecoxib and Structural Analogs- A Review
Sureshbabu Dadiboyena and Ashton T. Hamme II
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00162]
Cerium (III) Chloride as a Catalyst in the Clauson-Kaas Reaction: Synthesis and Reactivity of N-Aryl-2-thiocyanatopyrroles
Claudio C. Silveira, Margiani P. Fortes and Samuel R. Mendes
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00163]
Novel Glycomimetics: Anomeric and N-Glycosyl Sulfonamides
Pedro A. Colinas
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00164]
Molecular iodine: an Efficient and Versatile Reagent for Organic Synthesis
Sunil U. Tekale, Sushma S. Kauthale, Satish A. Dake, Swapnil R. Sarda and Rajendra P. Pawar
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00165]
Current Methods in Synthesis of Cyclic Oligonucleotides and Analogues
Maria Gaglione, Giovanni Di Fabio and Anna Messere
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00166]
Iron Nanoparticles-Catalyzed Electrophilic Amination of Functionalized Organocopper and Organozinc Reagents
Sukalyan Bhadra, Sabir Ahammed and Brindaban C. Ranu
[Abstract] [FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00167]
Abstracts
Cembrane Diterpenes: Chemistry and Biological Properties
Bin Yang, Xue-Feng Zhou, Xiu-Ping Lin, Juan Liu, Yan Peng, Xian-Wen Yang and Yonghong Liu
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00151]
Cembrane-type diterpenoids are a large and structurally varied group of natural products isolated from both terrestrial and marine organisms. The present paper reviews all the metabolites of cembrane diterpenes, reported up to 2010. The natural products discussed in this review can be divided into several different structural families featuring a variety of ring sizes and oxidation patterns. The currently known biological activities will be presented as well.
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Regioselectivity of the Liquid-phase Mononitration of Weakly Activated Arenes over Cross-linked Clays
Xinhua Peng, Xiongzi Dong and Yanfang Tai
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00152]
Methodology of a selection and environmental economy in nitration reaction of aromatics will be rather attractive to replace traditional sulfonitric acid process in industry. The cross-linked pillared clays originated from a natural bentonite show an obviously selective catalysis in nitration reaction of alkylbenzenes by respectively using nitric acid and a nitrogen dioxide/molecular oxygen system when compared with Kyodai-nitration. Several hydroxyl-aluminum cross-linked bentonites (Al-CLB, NH4Al-CLB, HAl-CLB, LaAl-CLB) were prepared in various conditions from a natural bentonite with polymeric cationic complexes of aluminum as pillars or cross-linkers. When they were applied in the nitration of weakly activated aromatic substrates, a para-preferential nitration is achieved.
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5-Aminouracil as Effective Inhibitor of Peroxyl Radicals: Experimental and Theoretical Studies
Stanislav A. Grabovskiy, Irina G. Konkina, Yuri I. Murinov and Natalia N. Kabal’nova
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00153]
The reaction of 5-aminouracil with peroxyl radicals generated by the thermal decomposition of 2,2′-azo-bis(2-methylpropionitrile) (AIBN) and 2,2′-azo-bis(2-amidinopropane) dihydrochloride was studied at 50°С in ethanol and water (pH 7.0) solution respectively. The oxidation product of 5-aminouracil formed by peroxyl radicals was dihydro-5,5,6-trihydroxypyrimidine-2,4-dione. The relative rate constant of 5-aminouracil vs. quercetin and 2,6-di-tert-butyl-4-methylphenol by peroxyl radicals generated from AIBN was measured in ethanol and found to be 0.19 (50°C) and 3.6 (70°C) respectively. Theoretical data of the redox potential and the bound dissociation energy oppose against single electron/proton transfer mechanism and provide support for a hydrogen atom abstraction mechanism. Transition structures and activation barriers of the hydrogen abstraction from 5-aminouracil, 5-hydroxy-6-methyluracil and 2,6-di-tert-butyl-4-methylphenol by methyl peroxyl radical were determined with the BB1K/6-31+G(d,p) level of theory. The relative theoretical reactivity was found to be in a good agreement with the experimental results and also supported the hydrogen abstraction mechanism.
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Preparation and Evaluation of Lysozyme Molecularly Imprinted Polymer Film on the Surface of Multi-wall Carbon Nanotubes
Guozhen Fang, Xiaorui Zhai, Qiliang Deng, Shifang Yuan, Meirong Cao and Shuo Wang
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00154]
Imprinting of macromolecule such as proteins with molecular imprinting technique remains challenge because of their bulkiness, structural complexity and sensitivity of denaturation. The purpose of this study was to synthesize a Lys-MIP film on the surface of the MWNTs by surface molecular imprinting technique, and subsequently selectively recognized and purified Lys from egg white. The Lys-MIP film was prepared using AAm as functional monomer, MBA as cross-linker, APS and TEMED as initiator under the optimized conditions. The polymer was characterized by TEM, FT-IR, TGA, and BET, as well. The equilibrium adsorption experiments and dynamic adsorption experiments were carried out to determine the binding capacity and the equilibrium time. The results showed that adsorption capacity of the Lys-MIP film was 20.89 mg g-1 at 0.50 mg mL-1, and adsorption capacity was 15.37 mg g-1 for the NIP. 82.10% of binging was obtained within 30 min and the adsorption equilibrium was achieved within 300 min. The selectivity adsorption experiments showed the Lys-MIP film had higher affinity and capacity for Lys than that for the competitive proteins, such as Cyt C, Mb, Hb and BSA. The relative selectivity coefficients for Lys/Cyt C, Lys/Mb, Lys/Hb, and Lys/BSA were 1.30, 1.30, 3.12 and 2.82, respectively. Purification experiment of Lys from egg white showed that adsorption capacity of the Lys-MIP film was 1.86 times more than that of the NIP. All these results proved that Lys-MIP film possessed high adsorption capacity and excellent selectivity. This material has great potential for separation of Lys in real samples.
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Regio- and Stereoselectivity of the 1,3-dipolar Cycloaddition of Pyridinium-3-olates and Pyrazinium-3-olates with Methyl Methacrylate: A Density Functional Theory Exploration
Lydia Rhyman, Hassan H. Abdallah, Sabina Jhaumeer-Laulloo, Luis R. Domingo, John A. Joule and Ponnadurai Ramasami
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00155]
Theoretical computations were performed on the 1,3-dipolar cycloaddition reactions of pyridinium-3-olates and pyrazinium-3-olates with methyl methacrylate employing density functional theory at the B3LYP/6-31G(d) level in the gas phase and in THF. The two possible regioisomeric pathways, forming 6-esters and 7-esters, along with the two stereoisomeric channels, endo and exo, have been considered. Thermodynamic and kinetic parameters calculated at room temperature have been analyzed while the regioselectivity has been interpreted using reactivity indices. The effect of the methyl group on the dipolarophile increases the activation energy but decreases the reaction enthalpy in THF. The rate constants of these reactions have been determined using conventional transition state theory. The thermodynamic and kinetic preferences for the reactions of these pyridinium-3-olates and pyrazinium-3-olates with methyl methacrylate, in the gas phase and THF, decrease in the order 6-exo > 7-exo > 6-endo > 7-endo. On comparing the reactions of pyridinium-3-olates and pyrazinium-3-olates with methyl acrylate, a different order is observed although the 6-exo cycloadduct remains the major product.
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Immobilized Ionic Liquids in Organic Chemistry
Manuela A. Pereira
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00156]
Due to its particular properties the use of ionic liquids in organic transformations is maturing. Immobilized ionic liquids, supported in different substrates or used as functional support, have found important applications in the last decade. In this review, a critical overview of the applications of immobilized ionic liquids in organic transformations as catalysts or to carry reagents or nanoparticles will be presented. Special relevance will be attributed to green procedure, use of nontoxic solvents and recover and reuse of materials. Metal catalysts, organocatalysts, asymmetric aldol reactions, functional group transformations, oxidations, reductions, biooligomer synthesis like oligosaccharide and peptide synthesis will be some of the transformations to be considered.
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Nucleophilic Participation in the Solvolyses of (Arylthio)methyl Chlorides and Derivatives: Application of Simple and Extended Forms of the Grunwald-Winstein Equations
Dennis N. Kevill, Young Hoon Park, Byoung-Chun Park and Malcolm J. D’Souza
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00157]
The specific rates of solvolysis of chloromethyl phenyl sulfide [(phenylthio)methyl chloride] and its p-chloro-derivative have been determined at 0.0 °C in a wide range of hydroxylic solvents, including several containing a fluroalcohol. Treatment in terms of a two-term Grunwald-Winstein equation, incorporating terms based on solvent ionizing power (YCl) and solvent nucleophilicity (NT) suggest a mechanism similar to that for the solvolyses of tert-butyl chloride, involving in the rate-determining step a nucleophilic solvation of the incipient carbocation in an ionization process. A previous suggestion, that a third-term governed by the aromatic ring parameter (I) is required, is shown both for the new and for the previously studied related substrates to be an artifact, resulting from an appreciable degree of multicollinearity between I values and a linear combination of NT and YCl values.
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Conjugated Polyelectrolytes: Synthesis and Application in Biomolecule Detection
Lingyun Wang, Huihui Li and Derong Cao
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00158]
Conjugated polyelectrolytes (CPEs) have attracted much attention as an emerging sensory material because of their meritorious signal amplification, convenient optical detection, readily tunable properties, and easy fabrication. This review paper summarizes the advances in synthesis of conjugated polyelectrolytes (such as polyfluorene, poly(para-phenylene ethynylene), poly(para-phenylene), poly(para-phenylene vinylene) and polythiophene, etc.) and their application in biomolecule detection. Additionally, new strategies to modify and optimize CPEs properties for specific applications are provided.
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Electroluminescent and Photovoltaic Properties of Silole-Based Materials
Huiying Fu and Yuanrong Cheng
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00159]
Recent investigations on silole derivatives have shown that materials based on siloles possess a number of intriguing properties, such as high charge carrier mobilities, high photoluminescence quantum yields, and good thermal stabilities, which are favorable for the applications in organic optoelectronic devices. Great achievements have been made in the silole-based conjugated materials for high performance optoelectronic devices. The recent development of silole-based materials for organic light-emitting diodes (OLEDs) and organic photovoltaic devices (OPVs) is described in this review. We will mainly focus upon the optoelectronic properties of substituted siloles, dibenzosiloles, and dithienosiloles.
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Applications of the in situ Propargyl-Allenyl Isomerization in Organic Synthesis
Yanpeng Xing, Yuxiu Wei and Hongwei Zhou
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00160]
Allenes have been shown to be versatile building blocks in organic synthesis. However, the diversity of the allene chemistry offers a challenging and exquisite task for organic chemists bent on building the suitable allene substrates. A good solution might be propargyl-allenyl isomerization, which means to prepare readily available propargyl substrates. This review focuses on recent progress in the in situ propargyl-allenyl isomerization in organic synthesis, published in 1990 and later.
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Stereoselective Biotransformations as an Effective Tool for the Synthesis of Chiral Compounds with P-C Bond – Scope and Limitations of the Methods
Ewa Żymańczyk-Duda and Magdalena Klimek-Ochab
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00161]
This article discusses advantages and limitations of the biotransformations with enzymes and whole-cell catalysts. It reviews biocatalytic synthesis of the chiral, organophosphorus compounds of different structures and characterizes their biological importance.
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Synthesis of Celecoxib and Structural Analogs- A Review
Sureshbabu Dadiboyena and Ashton T. Hamme II
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00162]
Non-steroidal anti-inflammatory drugs (NSAIDs) are an important class of therapeutics, incorporate a heterocyclic core in their molecular structure and are used for the alleviation of pain and inflammation associated with several pathological conditions. NSAIDs exert anti-inflammatory effects by inhibiting cyclooxygenase enzymes (COXs) which are useful in the synthesis of prostanoids generated from arachidonic acid. Selective COX-II inhibitors, compared to nonselective inhibitors exhibit reduced gastrointestinal, ulceration and renal side effects. In general, COX-II inhibitors incorporate a five or six-membered heterocyclic motif with built-in sulfonamide or methylsulfonate moiety. Celecoxib, a selective COX-II inhibitor drug, commercialized by Pfizer is applied in the treatment of rheumatoid arthritis, osteoarthritis, and painful menstruation related symptoms. The current review provides a discussion on the methodologies used to construct celecoxib/celebrex® and structural analogs.
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Cerium (III) Chloride as a Catalyst in the Clauson-Kaas Reaction: Synthesis and Reactivity of N-Aryl-2-thiocyanatopyrroles
Claudio C. Silveira, Margiani P. Fortes and Samuel R. Mendes
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00163]
A new and efficient methodology for the Clauson-Kaas synthesis of N-aryl pyrroles, employing CeCl3.7H2O as catalyst, was developed. The transformation was performed in acetonitrile under reflux, using conventional heating and microwave irradiation. Employing NH4SCN/Oxiall as a new thiocyanating system for the so obtained N-aryl pyrroles, the synthesis 1-aryl-2-thiocyanato-1H-pyrroles was also successfully accomplished. The latter served as starting materials for the high-yielding NaBH4-mediated preparation of 1,2-bis(1-(aryl)-1H-pyrrol-2-yl)disulfides and the phase transfer-mediated synthesis of 1-aryl-2-(trichloromethylthio)-1H-pyrroles.
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Novel Glycomimetics: Anomeric and N-Glycosyl Sulfonamides
Pedro A. Colinas
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00164]
Native glycosidic bonds in carbohydrates, are sensitive to the presence of enzymes. Thus, design of small molecule mimics (glycomimetics) is an active area of research. This review will focus on the development of a new class of glycomimetics: anomeric and N-glycosyl sulfonamides. These novel compounds have been demonstrated to be enzyme inhibitors or antiproliferative agents.
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Molecular iodine: an Efficient and Versatile Reagent for Organic Synthesis
Sunil U. Tekale, Sushma S. Kauthale, Satish A. Dake, Swapnil R. Sarda and Rajendra P. Pawar
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00165]
Molecular iodine has acquired an important role in organic synthesis due to its unique and powerful feature to catalyze organic transformations on account of its mild Lewis acidic character. The current review enlightens the versatile nature of the catalyst for numerous organic strategies including the synthesis of various heterocyclic compounds, iodination, protection- deprotection of functional groups etc.
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Current Methods in Synthesis of Cyclic Oligonucleotides and Analogues
Maria Gaglione, Giovanni Di Fabio and Anna Messere
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00166]
Cyclic oligonucleotides and analogues (cONs) are highly specific ligands for DNA, RNA and proteins. cONs are described in several diagnostic and therapeutic applications, as well as in elucidating enzyme mechanisms and as lead structures for development of new drugs because of their unusual chemical and biological properties in comparison with linear counterparts. In numerous structural studies it has been shown that conformational constraints imposed by circularity cause unique topologies, which in some cases can result into peculiar ON nanostructures. The wide field of applications of cONs has called for the definition of easy and efficient strategies to produce such compounds.
In this review, we will describe the enzymatic and chemical approaches reported for the synthesis of cONs with a particular focus on the chemical ones. We proceed following a chronological order from the earliest to the latest methods and improvements, describing at first the natural cyclic ONs and then modified linkages and cyclic analogues.
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Iron Nanoparticles-Catalyzed Electrophilic Amination of Functionalized Organocopper and Organozinc Reagents
Sukalyan Bhadra, Sabir Ahammed and Brindaban C. Ranu
[FULL-TEXT INQUIRY] [BSP/COC/E-Pub/00167]
The electrophilic amination of functionalized organocopper and organozinc reagents by N,N-dialkyl-O-benzoyl hydroxylamine derivatives to provide functionalized tertiary aryl amines has been accomplished efficiently at ambient temperature using in situ generated Fe(0) nanoparticles from Fe(acac)3. The formation and role of Fe(0)-nanoparticles were investigated. The mechanism involving Fe-assisted nucleophilic displacement at the nitrogen centre of the hydroxylamine derivative by the Cu/Zn-reagents is described. The organo-copper/zinc reagents are readily prepared by the treatment of the corresponding Grignard reagents with CuI and ZnCl2 respectively.
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