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Acid Derivatives (acid + derivative)
Kinds of Acid Derivatives Selected AbstractsOn the Way to Glycoprocessing Inhibitors , Synthesis of an Imidazolo-Nectrisine-Phosphono Acid Derivative: A Potential Glycosyltranferase InhibitorEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2003Théophile Tschamber Abstract Assuming the transition state of glycosyltransferase inhibitors to be similar to those encountered with potent glycosidase inhibitors , i.e. a flattened conformation with a positively charged anomeric centre , we worked out a synthesis of the D - arabino -configured phosphonic acid target molecule 2 derived from an imidazolo-sugar. The key synthetic intermediate is the linear imidazolo L - xylo compound 10 which could be obtained, either from L - threo precursor 6 by a coupling reaction with imidazole derivative 5, or from L -sorbose. A multi-step and site specific iodination of 10 gave the mono-iodo- L - xylo derivative 14 which was cyclised to the D - arabino -configured bicyclic azasugar 15. Phosphorylation of the Grignard derivative of the latter, followed by mono-esterification with citronellol along with some protection-deprotection steps led to target molecule 2. The potential inhibitor 2 is supposed to be protonated at its most basic N atom by a carboxylic acid residue in the arabinosyl-transferase active site. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Studies on Preparation and Fluorescent Properties of a Novel Photo-Sensitive Nanoparticle Composed of Europium Ion and Cinnamic Acid DerivativeMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 23 2009Dongjian Shi Abstract A novel fluorescent and photo-sensitive nanoparticle was self-assembled from an europium-based random copolymer, europium coordinated poly(methylacrylic acid)- co -poly(cinnamyl acrylate) (PMCFA-Eu3+), which was synthesized from methylacrylic acid (MAA), and Eu3+ -cinnamyl acrylate derivative (CFA) by radical polymerization. DLS and TEM results indicated the formation of spherical nanoparticles with 120,nm in diameter. The PMCFA-Eu3+ complex showed stronger fluorescence than Eu3+, indicating the effective energy transferred from the ligand to Eu3+. Moreover, the photo-crosslinking of the cinnamate groups induced a decrease in the diameter and an increase in the fluorescent properties of the PMCFA-Eu3+ nanoparticles. This functional nanoparticle might be useful as a carrier and a fluorescence probe in biomedical and fluorescent fields. [source] Synthesis of Tyrosinase Inhibitory Kojic Acid DerivativeARCHIV DER PHARMAZIE, Issue 3 2006Yong Sup Lee Abstract Kojic acid derivative 2 was synthesized by joining two pyrone rings through an ethylene linkage by Horner-Emmons reaction of phosphonate 6 with aldehyde 7. The intermediates 6 and 7 were derived from kojic acid. The tyrosinase inhibitory activity of 2 was about 8 times more potent (IC50 = 3.63 ,M) than that of kojic acid (IC50 = 30.61 ,M). Compound 2 also exhibited potent melanin synthesis inhibitory activity (19.53% inhibition at 5 ,g) indicating that the connection of two pyrone rings of kojic acid through a suitable linker can be an useful strategy for identification of potent tyrosinase inhibitiors. [source] Research Article: Effective and Specific Inhibition of the CD40,CD154 Costimulatory Interaction by a Naphthalenesulphonic Acid DerivativeCHEMICAL BIOLOGY & DRUG DESIGN, Issue 4 2010Emilio Margolles-Clark Costimulatory interactions are important regulators of T-cell activation and, hence, promising therapeutic targets in autoimmune diseases as well as in transplant recipients. Following our recent identification of the first small-molecule inhibitors of the CD40,CD154 costimulatory protein,protein interaction (J Mol Med 87, 2009, 1133), we continued our search within the chemical space of organic dyes, and we now report the identification of the naphthalenesulphonic acid derivative mordant brown 1 as a more active, more effective, and more specific inhibitor. Flow cytometry experiments confirmed its ability to concentration-dependently inhibit the CD154(CD40L)-induced cellular responses in human THP-1 cells at concentrations well below cytotoxic levels. Binding experiments showed that it not only inhibits the CD40,CD154 interaction with sub-micromolar activity, but it also has considerably more than 100-fold selectivity toward this interaction even when compared to other members of the tumor necrosis factor superfamily pairs such as TNF-R1,TNF-,, BAFF-R(CD268),BAFF(CD257/BLys), OX40(CD134),OX40L(CD252), RANK(CD265),RANKL(CD254/TRANCE), or 4-1BB(CD137),4-1BBL. There is now sufficient structure-activity relationship information to serve as the basis of a drug discovery initiative targeting this important costimulatory interaction. [source] ChemInform Abstract: Selective Decarboxylation: A Facile Synthesis of 3-Pyridinecarboxylic Acid Derivative.CHEMINFORM, Issue 15 2010Junhua Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Enantioselective Synthesis of a 3,5,5-Trialkylated Tetronic Acid Derivative.CHEMINFORM, Issue 23 2009Ken-ichi Takao 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Isolation and Synthesis of Methyl Bovinate, an Unusual Pulvinic Acid Derivative from Suillus bovinus (Basidiomycetes).CHEMINFORM, Issue 42 2008Helmut Besl 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Free Radical-Mediated Tandem Reaction of Dehydroamino Acid Derivative with ,-Allyl Palladium Complex: Synthesis of ,,,-Disubstituted Amino Acids.CHEMINFORM, Issue 25 2004Hideto Miyabe Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and Reactivity of a Stable Crystalline Diastereomerically Pure Trifluoromethanesulfinic Acid Derivative: (S)-(-)-1-Trifluoromethylsulfinyl-(R)-4-phenyloxazolidine-2-one.CHEMINFORM, Issue 43 2003Vadim D. Romanenko Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Efficient Asymmetric Synthesis of (S)-2-Ethylphenylpropanoic Acid Derivative, a Selective Agonist for Human Peroxisome Proliferator-Activated Receptor Alpha.CHEMINFORM, Issue 49 2002Masahiro Nomura Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Regio- and Stereoselective Synthesis of a trans-4-[60]Fullerenobisacetic Acid Derivative by a Tether-Directed Biscyclopropanation: A Diacid Component Applicable for the Synthesis of Regio- and Stereo-Regular [60]Fullerene Pearl-Necklace Polyamides.CHEMINFORM, Issue 47 2002Tetsuo Hino No abstract is available for this article. [source] ChemInform Abstract: (-)-Gibberic Acid (I): Hydrogen-Bonding Pattern of the Monohydrate of a Non-racemic Tetracyclic ,-Keto Acid Derivative of Gibberellin A3.CHEMINFORM, Issue 47 2001Hugh W. Thompson Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Julia,Colonna Stereoselective Epoxidation of Some ,,,-Unsaturated Enones Possessing a Stereogenic Center at the ,-Position: Synthesis of a Protected Galactonic Acid Derivative.CHEMINFORM, Issue 18 2001Peter C. Ray Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] "Tail,Tail Dimerization" of Ferrocene Amino Acid DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2010Daniel Siebler Abstract Acid anhydrides of N-protected 1,-aminoferrocene-1-carboxylic acid (Fca) have been prepared and spectroscopically characterized (protection group Boc, Fmoc, Ac; 4a,4c). The structure of the Boc-derivative 4a has been determined by single-crystal X-ray crystallography. An intramolecular N,H···O hydrogen bond involving the carbamate units results in a ring structure containing the two ferrocene units, the anhydride moiety, and the hydrogen bond. In the crystal, the individual molecules are connected by intermolecular N,H···O hydrogen bonds of the carbamate unit. Experimental and theoretical studies suggest that the ring motif is also a dominant species in solution. Electronic communication across the anhydride moiety is found to be very weak as judged from electrochemical, spectroscopic, and theoretical experiments. [source] Synthesis and Photophysical Studies of a Pyrenylindole and a Phenalenoindole Obtained from Dehydroamino Acid Derivatives , Application as Fluorescent Probes for Biological SystemsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2009Goreti Pereira Abstract Two pyrenyl-dehydroamino acid derivatives were cyclized by a metal-assisted C,N intramolecular cyclization developed in our research group, to give a pyrenylindole and a phenalenoindole. The pyrenylindole was inserted into a peptide by solid-phase coupling, with use of a 2-chlorotrityl chloride resin and a Fmoc strategy. The photophysical properties of the pyrenylindole and phenalenoindole in several solvents were studied and showed that these compounds can be used as fluorescence probes. The results obtained with the peptide labelled with the pyrenylindole moiety show potential for use of this compound as a fluorescence label avoiding the aggregation propensity of pyrene compounds. Photophysical studies of the pyrenylindole and of the phenalenoindole in lipid membranes were also carried out. Steady-state fluorescence anisotropy measurements revealed that both compounds adopt locations inside the lipid bilayers and are able to report the transition between the gel and liquid-crystalline phases. The results point to potential use of these compounds as fluorescent probes for biological systems.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and Biological Evaluation of Non-Hydrolyzable 1,2,3-Triazole-Linked Sialic Acid Derivatives as Neuraminidase InhibitorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2009Michel Weïwer Abstract ,-Sialic acid azide 1 has been used as a substrate for the efficient preparation of 1,2,3-triazole derivatives of sialic acid using the copper-catalyzed azide,alkyne Huisgen cycloaddition ("click chemistry"). Our approach is to generate non-natural N-glycosides of sialic acid that are resistant to neuraminidase-catalyzed hydrolysis as opposed to the natural O-glycosides. These N-glycosides would act as neuraminidase inhibitors to prevent the release of new virions. As a preliminary study, a small library of 1,2,3-triazole-linked sialic acid derivatives has been synthesized in 71,89,% yield. A disaccharide mimic of sialic acid has also been prepared using the ,-sialic acid azide 1 and a C-8 propargyl sialic acid acceptor in 68,% yield. A model sialic acid coated dendrimer was also synthesized from a perpropargylated pentaerythritol acceptor. These novel sialic acid derivatives were then evaluated as potential neuraminidase inhibitors using a 96-well plate fluorescence assay; micromolar IC50 values wereobserved, comparable to the known sialidase inhibitorNeu5Ac2en.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis of Substituted Oxazoles from N -Acyl-,-hydroxyamino Acid DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2008Paula M. T. Ferreira Abstract Several N -acyl-,-hydroxyamino acids were prepared and treated with di- tert -butyl dicarbonate in the presence of 4-(dimethylamino)pyridine, followed by treatment with N,N,N,,N, -tetramethylguanidine to give the corresponding N -acyldehydroamino acids in good to high yields. These were then treated with I2/K2CO3 followed by 1,8-diazabicyclo[5.4.0]undec-7-ene. The methyl esters of N -acyldehydroaminobutyric acid gave the corresponding substituted oxazoles in good to high yields. The N -acyldehydrophenylalanines gave 5-phenyloxazole derivatives in low to moderate yields together with ,-iododehydrophenylalanines. Under the same conditions, N -acyldehydroalanines failed to give the corresponding oxazoles. However, when the reaction was carried out in the absence of DBU, it was possible to isolate the ,,,-diiododehydroalanine derivatives. Although the reason for the different reactivities of the N -acyldehydroamino acids is not completely clear to us, cyclic voltammetry studies showed that the less-reactive derivatives have higher reduction potentials. This suggests that the double bonds in dehydroaminobutyric acid derivatives are more susceptible to electrophilic attack by iodine.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Straightforward Synthesis of Non-Natural Selenium Containing Amino Acid Derivatives and PeptidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2005Antonio L. Braga Abstract A series of non-natural selenium-containing amino acid derivatives and peptides have been synthesized, in a flexible and modular strategy. The peptide coupling reaction between N -protected amino acids and chiral ,-seleno amines afforded the desired products in high yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Asymmetric Synthesis of ,-Fluorinated ,-Amino Acid DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2005Deepak M. Shendage Abstract Asymmetric alkylation of (S)-Boc-BMI (1a, BMI = 2- tert -butyl-3-methylimidazolidin-4-one) and its ,-methyl derivative 1b with 2-fluoroallyl tosylate, subsequent mild acidic deprotection of the products 2a and 2b, and basic hydrolysis of the thus formed N -methylamides 4a and 4b gave (S)-2-amino-4-fluoropent-4-enoic acid (5a) and (S)-2-amino-4-fluoro-2-methylpent-4-enoic acid (5b). Basic hydrolysis of compound 4a was accompanied by partial racemization, which was overcome by applying a new stereoconservative deamidation procedure. The alkylated cis -configured product 2a formed under kinetic control epimerized on refluxing with 2 n NaOH to give the thermodynamically more stable trans isomer 9. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis of New Tetrazole-Substituted Pyroaminoadipic and Pipecolic Acid DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2005Fatimazohra Lenda Abstract Racemic 5-aryl- and 5-(arylmethyl)tetrazolyl-substituted pyroaminoadipic and pipecolic acid derivatives were diastereoselectively synthesized from dimethyl meso -2,5-dibromoadipate (1) in good yields under mild reaction conditions. The key step of this reaction sequence is the selective N2 -alkylation of 5-substituted tetrazoles with 1. The reactive 2-bromo-5-tetrazolyladipate derivatives 2a,g were generated and treated with sodium azide, followed by Pd/C-catalyzed hydrogenation, to provide lactams 4a,g. The chemoselective reduction of the amide carbonyl group of 4a,g with BH3, followed by acid hydrolysis, provided 5-tetrazolylpipecolic acids in racemic form. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Preparation of ,2 -Amino Acid Derivatives (,2hThr, ,2hTrp, ,2hMet, ,2hPro, ,2hLys, Pyrrolidine-3-carboxylic Acid) by Using DIOZ as Chiral Auxiliary,HELVETICA CHIMICA ACTA, Issue 8 2005Francois Gessier The title compounds were prepared from valine-derived N -acylated oxazolidin-2-ones, 1,3, 7, 9, by highly diastereoselective (,,90%) Mannich reaction (,,4,6; Scheme,1) or aldol addition (,,8 and 10; Scheme,2) of the corresponding Ti- or B-enolates as the key step. The superiority of the ,5,5-diphenyl-4-isopropyl-1,3-oxazolidin-2-one' (DIOZ) was demonstrated, once more, in these reactions and in subsequent transformations leading to various t -Bu-, Boc-, Fmoc-, and Cbz-protected ,2 -homoamino acid derivatives 11,23 (Schemes,3,6). The use of , -bromo-acyl-oxazolidinones 1,3 as starting materials turned out to open access to a variety of enantiomerically pure trifunctional and cyclic carboxylic-acid derivatives. [source] Amphiphilic Homochiral Oligopeptides Generated via Phase Separation of Nonracemic , -Amino Acid Derivatives and Lattice-Controlled Polycondensation in a Phospholipid EnvironmentHELVETICA CHIMICA ACTA, Issue 11 2003Irina Rubinstein Racemic S -ethyl thioesters of N, -stearoyllysine (=,S -ethyl (R,S)-2-amino-6-(stearoylamino)hexanethioate) and S -ethyl thioesters of , -stearyl glutamic acid (=stearyl (R,S)-4-amino-5-(ethylsulfanyl)-5-oxopentanoate) self-assemble as separated two-dimensional crystalline monolayers within an achiral phospholipid environment of racemic 1,2-dipalmitoylglycerol (DPG) and 1,2-dipalmitoylglycero-3-phosphoethanolamine (DPPE), as demonstrated by grazing-incidence X-ray-diffraction (GIXD) measurements performed on the surface of H2O. Lattice-controlled polycondensation within these crystallites with deuterium-enantiolabeled monomers was initiated by injecting aqueous solutions of Ag+ or I2/KI beneath the monolayers, which yielded mixtures of diastereoisomeric oligopeptides containing up to six to eight repeating units, as analyzed by MALDI-TOF mass spectrometry. Analysis of the diastereoisomeric distribution showed an enhanced relative abundance of the oligopeptides with homochiral sequences containing three or more repeating units. Within the DPPE monolayers, the nucleophilic amino group of the phospholipid operates as an initiator of polymerization at the periphery of the monomer two-dimensional crystallites. Enhanced relative abundance of enantiomerically enriched homochiral oligopeptides was obtained by the polycondensation of nonracemic monomers. This enhancement indicated a phase separation into racemic and enantiomorphous monomer crystallites within the phospholipid environment, although this separation could not be observed directly by GIXD. A possible role that might have been played by crystalline assemblies for the abiotic generation and amplification of oligopeptides with homochiral sequences is discussed. [source] Enantioselective Preparation of 2-Aminomethyl Carboxylic Acid Derivatives: Solving the ,2 -Amino Acid Problem with the Chiral Auxiliary 4-Isopropyl-5,5-diphenyloxazolidin-2-one (DIOZ).HELVETICA CHIMICA ACTA, Issue 6 2003Preliminary Communication Multigram amounts of suitably protected ,2 -amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3-acyl-4-isopropyl-5,5-diphenyloxazolidin-2-ones (acyl-DIOZ; 1) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55,90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2,8 thus obtained are converted to protected ,2 -amino acids by standard procedures (Table,1). Many of the DIOZ derivatives are highly crystalline compounds (31 X-ray crystal structures in Table,2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield. [source] A General Approach to the Synthesis of ,2 -Amino Acid Derivatives via Highly Efficient Catalytic Asymmetric Hydrogenation of ,-AminomethylacrylatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Yujuan Guo Abstract A new strategy was developed for the synthesis of a valuable class of ,-aminomethylacrylates via the Baylis,Hillman reaction of different aldehydes with methyl acrylate followed by acetylation of the resulting allylic alcohols and SN2,-type amination of the allylic acetates. Asymmetric hydrogenation of these diverse olefinic precursors using rhodium(Et-Duphos) catalysts provided the corresponding ,2 -amino acid derivatives with excellent enantioselectivities and exceedingly high reactivities (up to >99.5% ee and S/C=10,000). The first hydrogenation of (Z)-configurated substrates was studied for the synthesis of ,2 -amino acid derivatives. The high influence of the substrate geometry and steric hindrance on the reactivity and enantioselectivity was also disclosed for this reaction. This protocol provides a highly practical, facile and scalable method for the preparation of optically pure ,2 -amino acids and their derivatives under mild reaction conditions. [source] Asymmetric Synthesis of ,,,-Diaminophosphonic Acid Derivatives with a Catalytic Enantioselective Mannich ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Robert Djiokeng Momo Abstract Optically active ,,,-diaminophosphonic acid derivatives were obtained from the catalytic enantioselective Mannich reaction of phosphoglycine Schiff bases with N -Boc-imines, generated in situ from ,-amido sulfones. [source] Manganese-Promoted Regioselective Ring-Opening of 2,3-Epoxy Acid Derivatives: A New Route to ,-Hydroxy Acid DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Abstract A simple and general methodology directed towards the synthesis 3-aryl-2-hydroxy amides, or esters with total regioselectivity from the easily available 2,3-epoxy amides or esters, promoted by active manganese is described. Utilizing enantiopure epoxy amides as starting materials, the corresponding 3-aryl-2-hydroxy amides in enantiopure form are also available. Some synthetic applications of selected examples of 3-aryl-2-hydroxy carboxylic acid derivatives are shown. A mechanism has been proposed to explain this novel reaction. [source] Selective Oxidation of Acetophenones Bearing Various Functional Groups to Benzoic Acid Derivatives with Molecular OxygenADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Ryota Nakamura Abstract Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N,,N,, -trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)2] and THICA/Co(OAc)2/manganese(II) acetate [Mn(OAc)2]. For example, 4-methylacetophenone was selectively oxidized with molecular oxygen to 4-acetylbenzoic acid (85%) by THICA/Co(OAc)2 and to 4-methylbenzoic acid (93%) by Mn(OAc)2, while terephthalic acid was obtained in 93% with the THICA/Co(OAc)2/Mn(OAc)2 catalytic system. It is interesting that the acetyl group on the aromatic ring is efficiently converted by a very small amount of Mn(OAc)2 to the corresponding carboxylic acid, and that the present method provides a versatile route to acetylbenzoic acids which are difficult to prepare by conventional methods. [source] Copper(I)-Catalyzed Asymmetric Addition of Terminal Alkynes to ,-Imino Esters: An Efficient and Direct Method in the Synthesis of Chiral ,3 -Alkynyl ,2,2 -Dimethyl Amino Acid DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Jun Wang Abstract The first catalytic asymmetric addition of terminal alkynes to ,-imino esters was carried out using chiral copper(I) complexes as catalysts under mild reaction conditions, providing an efficient and direct synthetic approach to ,3 -alkynyl ,2,2 -dimethyl amino esters with yields of 73,97% and 48,90% ee. The rich chemistry of the alkynyl functionality makes the present method a powerful and versatile approach to a wide range of optically active ,2,2 -dimethyl amino acid derivatives. [source] 5-Aminolevulinic Acid Derivatives in Photomedicine: Characteristics, Application and PerspectivesPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2006Nicolas Fotinos ABSTRACT The introduction of lipophilic derivatives of the naturally occurring heme precursor 5-aminolevulinic acid (5-ALA) into photomedicine has led to a true revival of this research area. 5-ALA-mediated photodynamic therapy (PDT) and fluorescence photodetection (FD) of neoplastic disease is probably one of the most selective cancer treatments currently known in oncology. To date, this method has been assessed experimentally for the treatment of various medical indications. However, the limited local bioavailability of 5-ALA has widely prevented its use in daily clinical practice. Although researchers were already aware of this drawback early during the development of 5-ALA-mediated PDT, only recently have well-established concepts in pharmaceutical science been adapted to investigate ways to overcome this drawback. Recently, two derivatives of 5-ALA, methylaminolevulinate (MAL) and hexylaminolevulinate (HAL), gained marketing authorization from the regulatory offices in Europe and Australia. MAL is marketed under the trade name Metvix for the treatment of actinic keratosis and difficult-to-treat basal cell carcinoma. HAL has recently been launched under the trade name Hexvix to improve the detection of superficial bladder cancer in Europe. This review will first present the fundamental concepts underlying the use of 5-ALA derivatives in PDT and FD from a chemical, biochemical and pharmaceutical point of view. Experimental evidences from preclinical data on the improvements and limits observed with 5-ALA derivatives will then be introduced. The state-of-the-art from clinical studies with 5-ALA esters will be discussed, with special emphasis placed on the process that led to the development of MAL in dermatology and to HAL in urology. Finally, we will discuss promising medical fields in which use of 5-ALA derivatives might potentially lead to further use of this methodology in photomedicine. [source] Pd0/PR3 -Catalyzed Arylation of Nicotinic and Isonicotinic Acid Derivatives,ANGEWANDTE CHEMIE, Issue 7 2010Masayuki Wasa Direkt und vielseitig: Die intermolekulare C-H-Funktionalisierung von Pyridinringen an der 3- und 4-Position gelingt mit ArBr und einem Pd0/PR3 -Katalysator. Das leistungsfähige Verfahren ergibt vielfältige Nicotinsäure- und Isonicotinsäurederivate, die für die Wirkstoffentwicklung von großer Bedetung sind. [source] | |||||||||||||||||||||||||||||||||||||