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Pyrrolidine Derivatives (pyrrolidine + derivative)
Selected AbstractsChemInform Abstract: Facile Synthesis of Monofluoro ,-Lactones and Pyrrolidine Derivatives via Electrophilic Fluorination of Allenoic Acids and Amides.CHEMINFORM, Issue 20 2009Haifeng Cui 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: Stereoselective Synthesis of Pyrrolidine Derivatives via Reduction of Substituted Pyrroles.CHEMINFORM, Issue 17 2008Chao Jiang 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] Organocatalytic Asymmetric Multicomponent [C+NC+CC] Synthesis of Highly Functionalized Pyrrolidine Derivatives.CHEMINFORM, Issue 51 2007Ismail Ibrahem 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] Metal-Complex Catalysis During the Reduction of Functional Groups by Sodium Borohydride in the Synthesis of Pyrrolidine Derivatives.CHEMINFORM, Issue 44 2006A. O. Martirosyan 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] Stereoisomeric Synthesis of Oxazolidinone and Fused Pyrrolidine Derivatives via Azomethine Ylides and Their Antimicrobial Activity.CHEMINFORM, Issue 22 2003P. Pardasani No abstract is available for this article. [source] ChemInform Abstract: Organocatalytic Asymmetric Intramolecular [3 + 2] Cycloaddition: A Straightforward Approach to Access Multiply Substituted Hexahydrochromeno[4,3-b]pyrrolidine Derivatives in High Optical Purity.CHEMINFORM, Issue 38 2010Nan Li Abstract A chiral dinaphthyl-BINOL-derived phosphoric acid (NABIP) efficiently catalyzes the asymmetric intramolecular cycloaddition of formylphenoxybutenoates (I) and (IV) in the presence of ,-amino-,-aryl esters (II). [source] Synthesis and Glycosidase Inhibitory Activities of Pyrrolidines and Piperidines with N -(Polyhydroxyalkyl) Side ChainsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2007Sabrina Boutefnouchet Abstract Amidification of L -proline (3) with (+)-(R,R)- 6 and (,)-(S,S)-tartaric anhydride diacetate (7) gave N -substituted L -proline derivatives 8a,b, respectively. Acids 8a,b were transformed into diesters 9a,b with MeOH/HCl. Similar reactions with methyl (2S,4R)- 4 and (2R,4S)-4-acetoxypipecolate (5) led to bicyclic lactams 14a,b and 15a. Compounds 8a,b were converted into N -(trihydroxybutyl)pyrrolidine derivatives 8c,d, 10a,b and 11a,b. Methyl (2S,4R)- 20a and (2R,4S)-4-acetoxy- N -[(2S,3S)-1,2,3-trihydroxybutyl]pipecolate (20b) were obtained by displacement of (,)-(2S,2S)-2- O -benzyl-3,4- O -isopropylidene-1-deoxy-1-iodothreitol (19) by 4 and 5. Compounds 20a,b were converted into (2S,4R,2,S,2,S)- 21a and(2R,4S,2,S,3,S)-4-hydroxy-2-hydromethyl- N -(2-benzyloxy-3,4-isopropylidenedioxy)piperidine (21b) and finally into unprotected pentols 22a,b. Nonprotected (2S,2,S,3,S)- 11a and (2S,2,R,3,R)- N -(1,2,3-trihydroxybutyl)prolinol (11b), as well as 22a,b, did not inhibit any of the 13 glycosidases assayed. However, a triacetoxy derivative, (2S,3S)-2,3-diacetoxy-4-[(2R,4S)-4-acetoxy-2-(methoxycarbonyl)piperidin-1-yl]-4-oxobutanoic acid (13b) is an inhibitor (IC50 = 157 ,M) of ,- L -fucosidase from bovine kidney.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] An Efficient and Diastereoselective Intramolecular 1,3-Dipolar Cycloaddition of Cyclic Azomethine Ylides and NitronesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2006Rafael Pedrosa Abstract Nitrones and azomethine ylides formed by condensation of chiral 2-formyl-perhydro benzoxazines and N -substituted hydroxylamines or cyclic ,-amino acids cyclize intramolecularly yielding polycyclic isoxazolidine or pyrrolidine derivatives, respectively, with total diastereoselectivity. On the contrary, stabilized azomethine ylides derived from methyl prolinate undergo the cyclization products in very low yields.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Conformational analysis for some nonclassical antagonists of histamine H3 receptorINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 8 2007Ana Borota Abstract A conformational search in vacuum for a series of 1,3-substituted pyrrolidine derivatives has been performed using the AMBER, AM1, PM3, and MNDO methods. Conformational analysis of the pyrrolidine ligands suggests that these compounds could have many conformers that populate the low-energy minima on the potential energy surface (PES). The conformational space occupied by the ligands is large and, in vacuum, the rotation barriers of different flexible bonds have energies between 0.5 and thousands of kcal/mol. By optimization, most conformers have energy barriers of 0,5 kcal/mol; thus, they could interconvert easily to obtain better interactions in the receptor active site. Optimized conformers having energy barriers of >5 kcal/mol display bad geometries with very large bond lengths and deformed rings. Shapes and heights of rotation barriers obtained through COSMO,AM1 single-point calculations in water are similar to those obtained from single-point calculations in vacuum. However, in water the energy barriers are lower, allowing most conformers to convert in other low-energy conformers. The best conformers in vacuum and in water are different: the gas phase best conformer has a helical shape, while the best conformer in water has an extended shape. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Amine-Catalyzed Asymmetric Epoxidation of ,,,-Unsaturated AldehydesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2007Gui-Ling Zhao Abstract The direct organocatalytic enantioselective epoxidation of ,,,-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of ,,,-unsaturated aldehydes. In particular, protected commercially available ,,,-diphenyl- and ,,,-di(,-naphthyl)-2-prolinols catalyze the asymmetric epoxidation reactions of ,,,-unsaturated aldehydes with high diastereo- and enantioselectivities to furnish the corresponding 2-epoxy aldehydes in high yield with up to 97:3 dr and 98,% ee. The use of non-toxic catalysts, water and hydrogen peroxide, urea hydroperoxide or sodium percarbonate as the oxygen sources could make this reaction environmentally benign. In addition, one-pot direct organocatalytic asymmetric tandem epoxidation-Wittig reactions are described. The reactions were highly diastereo- and enantioselective and provide a rapid access to 2,4-diepoxy aldehydes. Moreover, a highly stereoselective one-pot organocatalytic asymmetric cascade epoxidation-Mannich reaction, which proceeds via the combination of iminium and enamine activation, is presented. The mechanism and stereochemistry of the amino acid- and chiral pyrrolidine-catalyzed direct asymmetric epoxidation of ,,,-unsaturated aldehydes are also discussed. [source] A New, Efficient and Stereoselective Synthesis of Tricyclic and Tetracyclic Compounds by Samarium Diiodide Induced Cyclisations of Naphthyl-Substituted Arylketones,An Easy Access to Steroid-Like SkeletonsCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2007Francesca Aulenta Dr. Abstract In this report, we present the application of samarium diiodide induced cyclisations of naphthyl-substituted ketones towards an easy and stereoselective access to tri- and tetracyclic-functionalised compounds. Typical naphthalene derivatives were studied to investigate the scope and limitations of this novel cyclisation process. The model substrates studied demonstrate that the samarium ketyl cyclisations are essentially restricted to the formation of six-membered rings. The diastereoselectivity of these reactions is strongly influenced by the connection of the alkyl side chain to the naphthalene core. ,-Naphth-1-yl-substituted ketones furnished cyclisation products, such as 17 or 22,26, as single diastereomers, whereas ,-naphth-2-yl-substituted precursors gave mixtures of diastereomers,as demonstrated by the conversion of model compound 10 into tricyclic products 18,a/18,b, or that of cyclohexanone derivative 33 into tetracyclic diastereomers 34,a/34,b. Cyclic ketones as ketyl precursors furnished steroid-like tetracyclic skeletons; however, due to the cis/cis fusion of rings B/C and C/D these products have an "unnatural" bowl-like shape. Several of the cyclisation products have been identified by X-ray analyses, which not only proved the constitutions, but also the relative configurations and the preferred conformations. Steroid analogue 23 was subjected to subsequent transformations, which demonstrate that the styrene-like double bond of such compounds can be used for further structural diversification. First attempts to synthesise related azasteroids by incorporating nitrogen atoms into the ketone moiety are also reported. Thus, pyrrolidine derivatives 44 and 47 as well as piperidine derivatives 50 and 52 were subjected to samarium diiodide induced cyclisations. The expected tetracyclic products 48, 49,a/49,b, 51 and 53,a/53,b were obtained in moderate to good yields. The stereoselectivities observed follow the rules already established for the all-carbon precursors. The resulting products, bearing a nitrogen atom in ring D, are interesting azasteroid analogues with "unnatural" configuration. [source] Studies on the Volatile Compounds of Roasted Spotted ShrimpCHEMISTRY & BIODIVERSITY, Issue 12 2004Toru Tachihara The aroma of spotted shrimp (Sergia lucence Hansen) was analyzed upon roasting to determine the components that constitute the characteristic roasted shrimp flavor. Our analyses resulted in the identification of ca.,200 volatiles, including high-impact sulfur and nitrogen compounds. In addition, we synthesized all possible stereoisomers of the pyrrolidine derivatives 1 and 4, and of the imine derivatives 16 and 18,20, which are very characteristic for the aroma. The odor evaluation of these chemicals revealed distinct differences, each possessing different aroma characteristics. [source] Unexpected Novel Binding Mode of Pyrrolidine-Based Aspartyl Protease Inhibitors: Design, Synthesis and Crystal Structure in Complex with HIV ProteaseCHEMMEDCHEM, Issue 1 2006Edgar Specker Dr. Abstract At present nine FDA-approved HIV protease inhibitors have been launched to market, however rapid drug resistance arising under antiviral therapy calls upon novel concepts. Possible strategies are the development of ligands with less peptide-like character or the stabilization of a new and unexpected binding-competent conformation of the protein through a novel ligand-binding mode. Our rational design of pyrrolidinedimethylene diamines was inspired by the idea to incorporate key structural elements from classical peptidomimetics with a non-peptidic heterocyclic core comprising an endocyclic amino function to address the catalytic aspartic acid side chains of Asp,25 and 25,. The basic scaffolds were decorated by side chains already optimized for the recognition pockets of HIV protease or cathepsin,D. A multistep synthesis has been established to produce the central heterocycle and to give flexible access to side chain decorations. Depending on the substitution pattern of the pyrrolidine moiety, single-digit micromolar inhibition of HIV-1 protease and cathepsin,D has been achieved. Successful design is suggested in agreement with our modelling concepts. The subsequently determined crystal structure with HIV protease shows that the pyrrolidine moiety binds as expected to the pivotal position between both aspartic acid side chains. However, even though the inhibitors have been equipped symmetrically by polar acceptor groups to address the flap water molecule, it is repelled from the complex, and only one direct hydrogen bond is formed to the flap. A strong distortion of the flap region is detected, leading to a novel hydrogen bond which cross-links the flap loops. Furthermore, the inhibitor addresses only three of the four available recognition pockets. It achieves only an incomplete desolvation compared with the similarly decorated amprenavir. Taking these considerations into account it is surprising that the produced pyrrolidine derivatives achieve micromolar inhibition and it suggests extraordinary potency of the new compound class. Most likely, the protonated pyrrolidine moiety experiences strong enthalpic interactions with the enzyme through the formation of two salt bridges to the aspartic acid side chains. This might provide challenging opportunities to combat resistance of the rapidly mutating virus. [source] | ||||||||||||||||||||||