1,721,041 research outputs found
Design and synthesis of new selective chemotherapeutic agents
No full textSynthesis of selective chemotherapeutic agents for antitumor and antiviral therapy purposes has been herein accomplished. Particularly, some novel molecular systems have been developed: Folic acid based chlorambucil conjugates for selective antitumor treatments. Folic acid based 5-aminolevulinic acid derivatives for photodynamic therapy of tumor cells. 4'-Substituted nucleosides and 2'3'-dihydro-1,4-dithiinyl nucleosides analogues for antiviral therapies. Six-membered sugar based modified oligonucleotides: ribo-CNA, (ribo-Cyclohexanyl Nucleic Acids)for gene expression contro
Recent Advances in Monosaccharide Synthesis: A Journey into L-Hexose World
No full textLast years have witnessed enormous progresses in glycomic field, mainly as a consequence of the crucial role carbohydrates have shown in biological systems. While up to a few years ago attention was mainly focused on the use of easily available D-sugars, a recent interest has emerged around their L-enantiomers, as they have been found to be key components of several bioactive compounds, whether in the form of oligosaccharides, glycopeptides, terpene glycosides or other clinically useful agents. However, L-sugars (L-hexoses especially) are rather rare in nature and not easily accessi-ble from inexpensive sources. As demand for their synthesis in considerable amount and high purity is more and more pressing, intense efforts have been addressed to the development of new and general methodologies for their construction. This review covers the synthetic routes to L-hexoses, mainly those coming from the new century. Methodologies for monosaccharide assembly will comprise de novo approaches, based on carbon chain elongation, hetero Diels-Alder reaction, asymmetric dihydroxylation up to the most recent amino acid-catalyzed aldol addition – as well as D-sugar manipulation strategies, including epimerization by chemical or enzymatic methods. Application of such protocols for the construction of biologically relevant oligosaccharides and natural products will be also briefly mentioned
Glycomimetics at the Mirror: Medicinal Chemistry of L-Iminosugars
No full textInhibition of carbohydrate processing enzymes is a topic of great interest, as these enzymes are involved in a plethora of key biochemical events, such as digestion, lysosomal catabolism of glycoconjugates and post-translational glycoprotein processing. Among the most potent inhibitors of such enzymes, iminosugars have emerged as versatile tools for medicinal chemists, especially those in quest for new therapeutic agents. Supply of iminosugars from natural sources or by chemical synthesis has provided excellent targets for medical intervention, ranging from antidiabetics and antivirals to inhibitors of genetic disorders. Although a huge body of literature has been reported around iminosugars, most data have focused on D-series iminosugars, whereas relatively little attention has been devoted to the corresponding L-enantiomers, due to their supposed lack of biological activity profile, as well as their scarce availability from natural sources. Notwithstanding, recent insights into the molecular details of enzyme-inhibitor interactions have led to a reassessment of L-iminosugars for pharmaceutical purposes. On one hand, they have been used as tools for intensive SAR (structure-activity-relationship) studies, in order to gain new information on the enzymatic inhibition mechanisms. Likewise, early reports on biological activity of Liminosugars have led to reconsider their therapeutic skills. This review focuses on the most significant discoveries regarding medicinal chemistry of L-iminosugars. The important role L-iminosugars play in unravelling the inhibition mechanisms of specific enzymes is herein recognized; moreover, the high potential of this class of inhibitors as novel drug candidates is under discussion
Challenges in carbohydrate chemistry: a survey of modern approaches for L-hexose stereoselective synthesis in Stereochemistry research trends
No full textStereochemistry is an important facet of chemistry. The study of stereochemical problems spans the entire range of organic, inorganic, biological, physical and supramolecular chemistries. Stereochemistry includes methods for determining and describing these relationships; the effect on the physical or biological properties these relationships impart upon the molecules in question, and the manner in which these relationships influence the reactivity of the molecules in question (dynamic stereochemistry). This book provides new research from around the globe on this field
Challenges in carbohydrate chemistry: a survey of modern approaches for L-hexose stereoselective synthesis
No full textStereochemistry is an important facet of chemistry. The study of stereochemical problems spans the entire range of organic, inorganic, biological, physical and supramolecular chemistries. Stereochemistry includes methods for determining and describing these relationships; the effect on the physical or biological properties these relationships impart upon the molecules in question, and the manner in which these relationships influence the reactivity of the molecules in question (dynamic stereochemistry). This book provides new research from around the globe on this field
Efficient Synthesis of ortogonally protected anti-2,3-diamino acids
No full textAn asymmetric synthesis of anti-2,3-diamino acids is reported. The enolates of N,N-dibenzylated b3-amino esters were treated with di-tert-butyl azodicarboxylate (DBAD) to afford their N0,N00-di-Boc-2-hydrazino derivatives with excellent anti diastereoisomeric ratio. Final Boc removal and reductive cleavage of the hydrazino bond led to the expected 2,3-diamino esters having only one free amino group. In comparison with other asymmetric C-2 amination procedures, this method does not need the use of expensive chiral reagents and/or chiral auxiliaries, while leads to products which can be orthogonally protected
Domino approach to a novel class of N-ribosyltransferase transition state analogues
No full textN-Ribosyltransferase inhibition represents a target of broad pharmacological relevance, given the crucial role of such enzymes in a number of disease-related events [1]. This is exemplified by the case of Immucillin-H, which picomolar activity has been exploited for diverse therapeutic purposes, e.g. treatment of leukemia, parasite-mediated diseases and autoimmune disorders. Herein a domino approach to the synthesis of novel iminosugar-based nucleoside, analogues of immucilin-H is proposed
Sulfur-assisted domino access to bicyclic dihydrofurans: case study and early synthetic applications
No full textA DDQ-mediated domino reaction (up to six steps in a single process) has been developed to selectively provide substituted dihydrofurans from a common starting material containing a cyclic bis-thioenol ether. Study of the reaction mechanism highlighted a role played by the sulfur-containing moiety in influencing reaction rate and stereoselectivity
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