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Ketone Moiety (ketone + moiety)
Selected AbstractsSynthesis of Functionalized Indoles with an ,-Stereogenic Ketone Moiety Through an Enantioselective Friedel,Crafts Alkylation with (E)-1,4-Diaryl-2-butene-1,4-dionesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Gonzalo Blay Abstract Chiral complexes of BINOL-based ligands with hafnium tert -butoxide catalyze the enantioselective Friedel,Crafts alkylation of indoles with (E)-1,4-diaryl-2-butene-1,4-diones at room temperature, with good yields and ee up to 94%. Hafnium(IV) was found to be a more effective Lewis acid than other frequently used metal ions such as titanium(IV) or zirconium(IV). Unlike the enantioselective Friedel,Crafts alkylation of indoles with ,,,-unsaturated compounds where the stereogenic center is generated in the ,-position to a carbonyl group, the Friedel,Crafts alkylation with 2-butene-1,4-diones described here generates an ,-stereogenic center with respect to one of the carbonyl groups. This can be regarded as an inversion of the normal reactivity pattern or umpolung. The enantioselective Friedel,Crafts alkylation of indoles with (E)-4-oxo-4-phenylbutenoates using a zirconium(IV)-BINOL catalyst is also reported. This reaction takes place regioselectively at the carbon in the ,-position to the ketone carbonyl group, generating an ,-ester stereogenic center. [source] Synthesis and properties of thermoplastic polyimides with ether and ketone moietiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2010Xiaohui Yu Abstract A series of polyimides containing ether and ketone moieties were synthesized from 1,3-bis(4-fluorobenzoyl) benzene and several commercially available dianhydrides via a conventional two-step polymerization. The inherent viscosities of Polyamide acids ranged from 0.46 to 0.73 dL/g. Thermal properties, mechanical properties, and thermalplasticity of the obtained polimide films were investigated by focusing on the chemical structures of their repeat units. These films were amorphous, flexible, and transparent. All films displayed low Tgs (184,225 °C) but also excellent thermal stability, the 5% weight loss temperature was up to 542 °C under nitrogen. The films showed outstanding mechanical properties with the modulus up to 3.0 GPa and the elongation at break in the range of 8,160%. The uniaxial stretching of PI-a at high temperature was studied owing to its excellent flexibility. The PI-a had an elongation at break up to 1600% at 245 °C and the uniaxially stretched film exhibited a much higher modulus (3.9 GPa) and strength (240 MPa) than undrawn film. The results indicated that PI-a can potentially be used to prepare materials such as fiber, ultra-thin film or ultra-high modulus film. All the obtained films also demonstrated excellent thermoplasticity (drop of E, at Tg > 103) which made the polyimides more suitable for melt processing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2878,2884, 2010 [source] Synthesis of trisubstituted thiophenes designed as progesterone receptor modulatorJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2006Weiqin Jiang When a known 2-[4-morpholino]-3-aryl-5-substituted thiophene, which showed moderate activity as a progesterone antagonist, was superimposed with a potent steroidal progesterone antagonist Org-33628, it showed a fair alignment in most parts of the molecules. According to the molecular modelling, displacement of the morpholine oxygen atom in the thiophene derivative with a carbonyl group would provide a better alignment with the C-3 carbonyl in Org-33628. Thus, a series of novel trisubstituted thiophenes bearing a cyclic ketone moiety was synthesized. Although these compounds only showed weak activities as progesterone receptor antagonists, all target compounds are novel and are fully characterized. [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] Fluorometric Investigation of the Acid-Base and Complexation Behaviour of Tetracycline and OxytetracyclineCHINESE JOURNAL OF CHEMISTRY, Issue 2 2004Hong-Xia Li Abstract The widely used antibiotics tetracyclines have been effectively used for ailing heart attack, ulcer cure and gene therapy. The actual mechanism of their activity has been proposed to link with the complexes with many metal ions. However, the sites at which complex formation takes place are not well established. In the present work, the deprotonation sequence of tetracycline (TC) and oxytetracycline (OTC), and their specific group used to bind europium ion were investigated by examining the character of fluorescence of TC and OTC as well as that of their complexes. It was concluded that the site of complexation is coordinated with the deprotonation sequence changing with the acidity/basicity of the solution. And it was inferred that five hydrogens in TC and OTC could be dissociated. The deprotonation sequence is as follows: C(3) hydroxy, C(10) phenol, C(4) dimethylamine, C(12) hydroxy and C(12a) hydroxy. The corresponding complexation site changed with pH increase in solution as follows: C(2) acylamino and C(3) hydroxy moiety, C(10)-C(11) ketophenol moiety, C(4) dimethylamine and C(3) hydroxy moiety, C(11)-C(12) ,-diketone moiety, C(12) hydroxy and C(12a) hydroxy moiety, and C(12) hydroxy and C(1) ketone moiety respectively. [source] | |||||||||||||||||||