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Synthetic Chemistry (synthetic + chemistry)
Selected AbstractsRecent Developments in Synthetic Chemistry, Chiral Separations, and Applications of Tröger's Base AnaloguesHELVETICA CHIMICA ACTA, Issue 3 2009Sergey Sergeyev Abstract Tröger's base is a well-known chiral molecule with a few unusual structural features. The chemistry of Tröger's base analogues has been greatly developed over the last 20 years, and numerous interesting applications in supramolecular chemistry and in molecular recognition have emerged. This Review gives a short overview of the chemistry of Tröger's base and its analogues, with particular focus on recent achievements in synthesis, enantiomer separations, and applications. [source] ,-Lithio Quinuclidine N-Oxide (Li-QNO): A New Base for Synthetic Chemistry.CHEMINFORM, Issue 11 2007Ian A. O'Neil Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Screening for Novel Industrial BiocatalystsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 6 2004P. Lorenz Abstract Biocatalysis, the use of microbial cells or isolated enzymes in the production of fine chemicals, is steadily moving towards becoming accepted as an indispensable tool in the inventory of modern synthetic chemistry [1]. It is estimated that in 10,% of the cases biocatalysis will provide an overall superior synthetic strategy over traditional organic chemistry [2]. This remarkable development in a field coined "white biotechnology" is due to the growing recognition in the industry of the capabilities and performance of enzymes as exemplified in a growing number of implemented processes [3,,4], examples running at a scale of >1000 tons product/year. Breakthroughs in the key biotechnological areas of a) genetic resource access (explicitly the explorability of non-cultivated microorganisms), b) enzyme screening and discovery and c) in vitro evolution of proteins to find and optimize enzymes to become near-ideally suited biocatalysts have been instrumental in pushing industrial biocatalysis to where it stands today [5, 6]. With these technological options it seems that future use of biocatalysis is limited only by the availability of the biocatalyst [3], the screening for which is subject of this review. [source] A Microfluidic Approach to the Rapid Screening of Palladium-Catalysed Aminocarbonylation ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Philip Abstract The evaluation and selection of the most appropriate catalyst for a chemical transformation is an important process in many areas of synthetic chemistry. Conventional catalyst screening involving batch reactor systems can be both time-consuming and expensive, resulting in a large number of individual chemical reactions. Continuous flow microfluidic reactors are increasingly viewed as a powerful alternative format for reacting and processing larger numbers of small-scale reactions in a rapid, more controlled and safer fashion. In this study we demonstrate the use of a planar glass microfluidic reactor for performing the three-component palladium-catalysed aminocarbonylation reaction of iodobenzene, benzylamine and carbon monoxide to form N -benzylbenzamide, and screen a series of palladium catalysts over a range of temperatures. N -Benzylbenzamide product yields for this reaction were found to be highly dependent on the nature of the catalyst and reaction temperature. The majority of catalysts gave good to high yields under typical flow conditions at high temperatures (150,°C), however the palladium(II) chloride-Xantphos complex [PdCl2(Xantphos)] proved to be far superior as a catalyst at lower temperatures (75,120,°C). The utilised method was found to be an efficent and reliable way for screening a large number of palladium-catalysed carbonylation reactions and may prove useful in screening other gas/liquid phase reactions. [source] Synthetic Applications of Laccase in Green ChemistryADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Suteera Witayakran Abstract Laccases (benzenediol:oxygen oxidoreductase, EC 1.10.3.2), multi-copper-containing oxidoreductase enzymes, are able to catalyze the oxidation of various low-molecular weight compounds, specifically, phenols and anilines, while concomitantly reducing molecular oxygen to water. Because of their high stability, selectivity for phenolic substructures, and mild reaction conditions, laccases are attractive for fine chemical synthesis. This review provides a discussion of the recent applications of this interesting enzyme in synthetic chemistry, including laccase and laccase-mediator catalyzed reactions. In addition, the review also includes a brief discussion of the distribution of laccase in nature, enzyme structure, and the catalytic mechanism which are of relevance to their applications as biocatalysts. [source] Recent cancer drug development with xanthone structuresJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2009Younghwa Na Abstract Objectives Xanthones are simple three-membered ring compounds that are mainly found as secondary metabolites in higher plants and microorganisms. Xanthones have very diverse biological profiles, including antihypertensive, antioxidative, antithrombotic and anticancer activity, depending on their diverse structures, which are modified by substituents on the ring system. Although several reviews have already been published on xanthone compounds, few of them have focused on the anticancer activity of xanthone derivatives. In this review we briefly summarize natural and synthetic xanthone compounds which have potential as anticancer drugs. Key findings The interesting structural scaffold and pharmacological importance of xanthone derivatives have led many scientists to isolate or synthesize these compounds as novel drug candidates. In the past, extensive research has been conducted to obtain xanthone derivatives from natural resources as well as through synthetic chemistry. Xanthones interact with various pharmacological targets based on the different substituents on the core ring. The anticancer activities of xanthones are also dramatically altered by the ring substituents and their positions. Summary The biological activities of synthetic xanthone derivatives depend on the various substituents and their position. Study of the biological mechanism of action of xanthone analogues, however, has not been conducted extensively compared to the diversity of xanthone compounds. Elucidation of the exact biological target of xanthone compounds will provide better opportunities for these compounds to be developed as potent anticancer drugs. At the same time, modification of natural xanthone derivatives aimed at specific targets is capable of expanding the biological spectrum of xanthone compounds. [source] Copolymerization of carbon dioxide and epoxideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2004Hiroshi Sugimoto Abstract An erratum has been published for this article in J Polym Sci Part A: Polym Chem (2005) 43(4) 916. The alternating copolymerization of carbon dioxide and epoxide to produce polycarbonate has attracted the attention of many chemists because it is one of the most promising methodologies for the utilization of carbon dioxide as a safe, clean, and abundant raw material in synthetic chemistry. Recent development of catalysts for alternating copolymerization is based on the rational design of metal complexes, particularly complexes of transition metals with well-defined structures. In this article, the history and recent successful examples of the alternating copolymerization of carbon dioxide and epoxide are described. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5561,5573, 2004 [source] Synthesis and NMR solution structure of an ,-helical hairpin stapled with two disulfide bridgesPROTEIN SCIENCE, Issue 5 2000Philippe Barthe Abstract Helical coiled-coils and bundles are some of the most common structural motifs found in proteins. Design and synthesis of ,-helical motifs may provide interesting scaffolds that can be useful as host structures to display functional sites, thus allowing the engineering of novel functional miniproteins. We have synthesized a 38-amino acid peptide, ,2p8, encompassing the ,-helical hairpin present in the structure of p8MTCP1, as an ,-helical scaffold particularly promising for its stability and permissiveness of sequence mutations. The three-dimensional structure of this peptide has been solved using homonuclear two-dimensional NMR techniques at 600 MHz. After sequence specific assignment, a total of 285 distance and 29 dihedral restraints were collected. The solution structure of ,2p8 is presented as a set of 30 DIANA structures, further refined by restrained molecular dynamics, using simulated annealing protocol with the AMBER force field. The RMSD values for the backbone and all heavy atoms are 0.65 ± 0.25 and 1.51 ± 0.21 Å, respectively. Excised from its protein context, the ,-hairpin keeps its native structure: an ,-helical coiled-coil, similar to that found in superhelical structures, with two helices spanning residues 4-16 and 25,36, and linked by a short loop. This motif is stabilized by two interhelical disulfide bridges and several hydrophobic interactions at the helix interface, leaving most of its solvent-exposed surface available for mutation. This ,-helical hairpin, easily amenable to synthetic chemistry and biological expression system, may represent a stable and versatile scaffold to display new functional sites and peptide libraries. [source] Preparation of N -alkylpyridinium aryl ketone derivatives via the surfactant promoted cross-coupling reaction of N -alkylpyridiniumboronic acids with carboxylic anhydride in water at room temperatureAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2009H. Matondo Abstract The palladium (II) chloride catalyzed coupling reaction of N -alkylpyridiniumboronic acids with benzoic anhydride was carried out smoothly in water to give high yields of ketones without the use of a phosphine ligand. The reaction was conducted under mild conditions at room temperature. In this article, by focusing on the Suzuki reaction, it is shown how this method can impact modern synthetic chemistry, making reactions faster, easier and cleaner. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||