Most Cited Articles:

Abstracts


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Ionic Liquids in Carbohydrate Chemistry - Current Trends and Future Directions
Murugesan, Saravanababu, Linhardt, Robert J

Room Temperature Ionic Liquids (RTILs) have recently been introduced as new solvents in the chemical and biotechnological arenas. Carbohydrates are important natural products that play important biological and commercial roles as foods, drugs and chemical feedstocks. They have two properties that complicate their use a low solubility in most solvents and complex, highly chiral structures. We are currently witnessing a rapid increase in novel applications for newly discovered RTILs. This account reviews the application of RTILs in carbohydrate chemistry and biochemistry as a mono / biphasic solvent, a solvent / catalyst and a product retrieval media.


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Recent Carbohydrate-Based Chemoselective Ligation Applications
Joseph M. Langenhan, Jon S. Thorson

Chemoselective ligation reactions are highly efficient and specific covalent bond forming reactions capable of proceeding within a physiological environment. Chemoselective ligations offer exquisite specificity, similar to enzymatic reactions, but with the significant advantage of accessing a much broader range of coupling partners. Thus, even among a multitude of reactive functional groups, two ligation partners exclusively react with one another. While chemoselective ligation has been used in many applications, the focus of this review is the application of chemoselective ligation reactions toward carbohydrate-based structures. More specifically, recent applications are presented in areas such as immobilized carbohydrate arrays, cell-surface engineering, glycoproteins/peptides, and glycosylated natural products.


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Recent Advances in Microwave-Assisted Synthesis of Heterocyclic Compounds
Molteni, Valentina, Ellis, David A

Heterocyclic scaffolds represent the central framework of many biologically active compounds. The goal of this review is to present advances in the field of microwave-assisted synthesis of heterocyclic compounds that have been described in the literature since 1994. In particular, it focuses on reactions in which a heteroatom is directly participating in the bond forming process that gives rise to a heterocyclic core. The review is divided into two sections, cycloaddition and cyclization reactions, which are further classified according to ring type. These reactions are discussed from a synthetic standpoint with emphasis on comparison between microwave and conventional techniques.


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Sialic Acid Donors: Chemical Synthesis and Glycosylation
Ress D.K, Linhardt R.J

Sialic acids (or ulosonic acids) are a family of acidic ketoses (including neuraminic acid, KDN and KDO) that are found at the non-reducing terminus of many glycoconjugates. These saccharide residues are recognized ligands of protein lectins and are removed in the first step in glycoconjugate catabolism. Moreover, sialic acid containing carbohydrates, such as glycolipid gangliosides (i.e. GM3), glycopeptides (i.e. Tn) and polysaccharides (i.e. polysialic acid or colominic acid) play important biological roles. Thus, they represent important targets in natural product synthesis. This review examines the application of sialic acids as donors in glycosylation reactions. The synthesis of protected sialic acid donors and challenges associated with their use in the synthesis of heteronuclear and carbon glycosides are discussed.


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Carbohydrate Scaffolds for the Production of Bioactive Compounds
Cipolla, L, Peri, F, Ferla, B. L, Redaelli, C, Nicotra, F

Recent efforts in the use of carbohydrates as scaffolds for the production of bioactive compounds are reported. Orthogonally protected and solid phase supported monosaccharides for the production of libraries, exploiting the combinatorial approach by derivatisation of each hydroxyl group with different pharmacophores, are described. Example of peptidomimetics synthesised on a carbohydrate skeleton orienting proper amino acid residues, are also reported. In order to increase the conformational rigidity of the sugar templates, a variety of original bicyclic or policyclic polyfunctionalised structures have been synthesised from carbohydrates. Same of them have spiro or condensed bicyclic structures, others include one or more sugars in a macrocyclic framework or in cyclopeptides in order to induce bioactive peptide loops.


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Indium(I) Compounds in Organic Synthesis
Peppe C

Indium metal and selected indium(III) compounds have emerged as an alternative tool in organic synthesis, but the use of compounds with the metal at the oxidation state (I) has been hardly explored. This account discusses the major routes to indium(I) compounds, their chemical properties and applications in organic synthesis.


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Synthesis of Five- and Six-Membered Heterocycles Through Palladium- Catalyzed Reactions
Kirsch G, Hesse S, Comel A

Over the last years, palladium-catalyzed coupling reactions have been extensively studied and the names of Heck, Stille, Suzuki and Sonogashira are well known for their contribution to this chemistry. Extension of the coupling reactions allowing introduction of heteroatoms have followed and the Buchwald-Hartwig reaction is now a concept for this chemistry.

Another achievement in this field is the possibility offered by the methodology to acceed to heterocyclic compounds either through a direct construction of the heterocyclic ring or by a two-step procedure (coupling followed by an heteroannulation).

We are in the following paper going to review these ways of preparing heteroaromatic compounds either as single ring system or condensed to other aromatic rings.


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Current Strategies for the Synthesis of RNA
Muller S, Wolf J, Ivanov S.A

The biological potential of RNA along with the variety of possible applications has led to an increased demand for large-scale production of RNA molecules. Recent developments in the field allow for the synthesis of long RNA molecules (up to 100 nts) of excellent quality. This review focuses on current strategies (i.e. 2'-O-TBDMS, 2'-O-TOM and 2'-O-ACE chemistry) for chemical RNA synthesis.


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Benziodoxole-Based Hypervalent Iodine Reagents in Organic Synthesis
Viktor V. Zhdankin

Five-membered hypervalent iodine heterocycles derived from benziodoxole and benziodazole oxide have recently emerged as reagents of choice for various synthetically useful oxidative transformations. In particular, IBX (2-iodoxybenzoic acid) and DMP (Dess-Martin periodinane) are widely used for the selective oxidation of primary and secondary alcohols and for a variety of other important oxidations. IBX-amides and IBX-esters are a new class of pentavalent iodine reagents with a pseudo-benziodoxole structure and a reactivity pattern similar to IBX.


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Useful Reactions in Modern Pheromone Synthesis
Mori K, Tashiro T

Various aspects of pheromone synthesis are reviewed by analyzing examples published between 1990 and early 2003. Syntheses executed with new methodologies such as organoborane reactions, organotransition metal chemistry including olefin metathesis, asymmetric epoxidation, asymmetric dihydroxylation, other asymmetric chemical processes, and stereoselective biocatalysis are selected to illustrate the usefulness of new reactions in pheromone synthesis.