Book Volume 12
Page: 1-80 (80)
Author: Didier Desmaele
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Acyclic polyisoprenoids are ubiquitous in nature from bacteria to human cells. Beside, their leading role as precursor of thousands of cyclic terpenoids, they have also a tremendous importance as membrane constituents, protein modulators and nanoparticle carrier material. Their synthesis is a main topic since the dawn of organic chemistry, nevertheless today there is still no universal method to access these compounds and it remains space for finding original and efficient solutions. In this review we provided an overview of the synthetic methods available for the synthesis of head-to-tail and tail-to-tail 1,5-diene-containing polyprenyl derivatives, including alkylation reactions of organometallics and heteroatom stabilized carbanions, sigmatropic rearrangements, transition metal catalyzed methods and also biocatalytic syntheses. The synthesis of small difunctionnal building blocks from cheap naturally occurring polyprenols such as geraniol or farnesol are described. A special emphasis will be given on the coupling of polyisoprenoid chains to carbocycles including synthesis of isoprenoid quinones.
Page: 81-116 (36)
Author: Irina Carlescu, Daniela Apreutesei Wilson, Gabriela Lisa, Nicolae Hurduc and Dan Scutaru
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This chapter describes the influence of micromolecular structure on selfassembly macroscopic properties of liquid crystalline ordered systems and focuses on structure-properties relationships of some thermotropic monosubstituted ferrocenomesogens obtained in our research group. The structural features evaluated are the connectivity between ferrocene and mesogenic units, the number of aromatic rings and the types of linking and ending groups responsible for mesomorphic behavior. It is shown that systems based on monosubstituted ferrocene derivatives exhibit unique liquid crystalline properties which may be used for designing materials with specific functions and properties. The aim of this paper is to present essentially the work carried out in our laboratory over a period of 10 years therefore; this chapter will focus on the main conclusions drawn on our own synthesized ferrocenomesogens.
Page: 117-150 (34)
Author: Mihaela Gulea
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The present review focuses on the synthesis and applications of phosphorothioates (phosphorothioic esters) with the general structure R2P(O)SR’, which are molecules belonging to the large family of organophosphorus compounds. They found important applications as biological active molecules, as well as synthetic intermediates to access valuable phosphorus and/or sulfur-containing structures. The reactivity of both heteroatoms, phosphorus and sulfur, is discussed by showing how they are involved as electrophilic, nucleophilic, or radical species in different transformations. The general methods for the preparation of phosphorothioates are described according to the various strategies involving P-S bond formation from one sulfur-reagent and one phosphorus-reagent, which include recent metal-catalyzed cross-coupling reactions. Particular attention is paid to synthetic applications of phosphorothioates occurring via the P-S bond cleavage, including for example anionic rearrangements and cascades, formation of sulfur-heterocycles, homolytic processes for olefins phosphorylation, and metal-catalyzed alkynes thiophosphorylation. The literature of the last two decades is covered, highlighting selected contributions in the chemistry of this class of compounds.
Kinetic Resolution Using Diastereoselective Acylating Agents as a Synthetic Approach to Enantiopure Amines
Page: 151-199 (49)
Author: Galina L. Levit, Dmitry A. Gruzdev and Victor P. Krasnov
The kinetic resolution (KR) of racemates is one of the most important modern approaches to prepare optically pure substances. This method is based on the difference in the reaction rates of enantiomers under the action of chiral resolving agents or catalysts. KR as a result of the acylation reaction (acylative KR) has been widely used to obtain enantiopure amines that are valuable precursors and structural fragments of biologically active compounds and pharmaceuticals. The nonenzymatic acylative KR of racemic amines is usually carried out in the presence of chiral acyltransfer catalysts or by the action of enantioselective or diastereoselective lowmolecular weight acylating agents. This review surveys the research work on KR of racemic amines under the action of chiral diastereoselective acylating agents. This approach has recently received a very significant development, which is due to the availability of various reagents of this kind, as well as the ease of process implementation. Application of derivatives of chiral acids, including natural amino acids, 2-arylpropionic acids, 2-oxy-carboxylic acids, etc. as acylating agents in the KR processes makes it possible to obtain amines of various classes and related compounds with a very high enantiomeric purity, which is often inaccessible in other nonenzymatic methods. Diastereoisomerically enriched (pure) amides formed as a result of acylative KR of racemic amines may themselves be of interest for further synthetic transformations.
Page: 200-252 (53)
Author: Vadim D. Romanenko
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This chapter deals with the synthesis of α-organyl-substituted methylenebisphosphonates and focuses on compounds not having the heteroatomic substituents at the geminal carbon. We present different methodologies on the basis of the reactivity of monophosphonate and methylene 1,1-bisphosphonate systems including the Michaelis-Arbuzov and Michaelis-Becker reactions, substitutions, Michael additions, cycloaddition, as well as more specific approaches. Together with the synthetic methods, the biomedical application of the compounds is also described.
Advances in Organic Synthesis is a book series devoted to the latest advances in synthetic approaches towards challenging structures. The series presents comprehensive reviews written by eminent authorities on different synthetic approaches to selected target molecules and new methods developed to achieve specific synthetic transformations or optimal product yields. Advances in Organic Synthesis is essential reading for all organic chemists in academia and the industry who wish to keep abreast of rapid and important developments in the field.</p> <p> This volume presents the following reviews:</p> <p>• Stereoselective Methodologies for the Synthesis of Acyclic Polyisoprenoids</p> <p>• Monosubstituted Ferrocene-Containing Thermotropic Liquid Crystals </p> <p>• Progress in the Chemistry of Phosphorothioates </p> <p>• Kinetic Resolution Using Diastereoselective Acylating Agents as a Synthetic Approach to Enantiopure Amines </p> <p>• Advances in the Synthesis of Functional α-Organyl gem-Bisphosphonates for Biomedical Applications.</p>