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Lorenzo CaggianoDamiano Castoldi Raphael BeumerPau Bayón Joachim TelserCesare Gennari 《Tetrahedron letters》2003,44(43):7913-7919
During the course of our synthetic studies towards simplified eleuthesides, we have found that p-methoxyphenyl (PMP) protected allylic alcohols are compatible with the RCM reaction and can give better yields than the corresponding free allylic alcohols. 相似文献
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Depecker G Patino N Di Giorgio C Terreux R Cabrol-Bass D Bailly C Aubertin AM Condom R 《Organic & biomolecular chemistry》2004,2(1):74-79
A cyclic molecule including a hexameric PNA sequence has been designed and synthesized in order to target the TAR RNA loop of HIV-1 through the formation of a "kissing complex". For comparison, its linear analogue has also been investigated. The synthesis of the cyclic and linear PNA has been accomplished following a liquid-phase strategy using mixed PNA and fully N-protected (aminoethylglycinamide) fragments. The interactions of this cyclic PNA and its linear analogue with TAR RNA have been studied and the results indicate clearly that no interaction occurs between the cyclic antisense PNA and TAR RNA, whereas a tenuous interaction has been detected with its linear PNA analogue. 相似文献
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C. Ahern R. Darcy F. O'Keeffe P. Schwinté 《Journal of inclusion phenomena and macrocyclic chemistry》1996,25(1-3):43-46
6-Perhydroxyalkylamino-6-perdeoxy--cyclodextrins have been synthesised by treating 6-perbromo-6-perdeoxy-cyclodextrins with hydroxyalkylamines. The products (1, 2) are precursors of dendrimeric cyclodextrins in which the cavity provides access for the guest to interact with the branches. A fluorescence study has demonstrated the effects of the branches on binding of anilinonaphthalene sulfonate probes. The hosts show selectivity towards guests, and pH-dependence of binding, consistent with polar interaction between guest sulfonate anions and the protonated amino groups of the dendrimeric structure. 相似文献
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Choi S Cooley RB Voutchkova A Leung CH Vastag L Knowles DE 《Journal of the American Chemical Society》2005,127(6):1773-1781
Many transition-metal complexes mediate DNA oxidation in the presence of oxidizing radiation, photosensitizers, or oxidants. The DNA oxidation products depend on the nature of the metal complex and the structure of the DNA. Earlier we reported trans-d,l-1,2-diaminocyclohexanetetrachloroplatinum (trans-Pt(d,l)(1,2-(NH(2))(2)C(6)H(10))Cl(4), [Pt(IV)Cl(4)(dach)]; dach = diaminocyclohexane) oxidizes 2'-deoxyguanosine 5'-monophosphate (5'-dGMP) to 7,8-dihydro-8-oxo-2'-deoxyguanosine 5'-monophosphate (8-oxo-5'-dGMP) stoichiometrically. In this paper we report that [Pt(IV)Cl(4)(dach)] also oxidizes 2'-deoxyguanosine 3'-monophosphate (3'-dGMP) stoichiometrically. The final oxidation product is not 8-oxo-3'-dGMP, but cyclic (5'-O-C8)-3'-dGMP. The reaction was studied by high-performance liquid chromatography, (1)H and (31)P nuclear magnetic resonance, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The proposed mechanism involves Pt(IV) binding to N7 of 3'-dGMP followed by nucleophilic attack of a 5'-hydroxyl oxygen to C8 of G and an inner-sphere, 2e(-) transfer to produce cyclic (5'-O-C8)-3'-dGMP and [Pt(II)Cl(2)(dach)]. The same mechanism applies to 5'-d[GTTTT]-3', where the 5'-dG is oxidized to cyclic (5'-O-C8)-dG. The Pt(IV) complex binds to N7 of guanine in cGMP, 9-Mxan, 5'-d[TTGTT]-3', and 5'-d[TTTTG]-3', but no subsequent transfer of electrons occurs in these. The results indicate that a good nucleophilic group at the 5' position is required for the redox reaction between guanosine and the Pt(IV) complex. 相似文献
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Based on theoretical thermodynamic principles, the possibility of environmental degradation of polyacrylamide to its starting monomer was investigated. Theoretical electronic structure studies on the geometry and fragmentation energy of acrylamide and N,N‐dimethyl acrylamide tetramer models were carried out using a first principles gradient corrected density functional approach. Thermal degradation to form a radical would require the cleavage of carbon–carbon bonds in the polymer chain; the energy needed for this cleavage was found to depend on the structure of the repeat unit which ranged from low of 72.5 kcal for a rare head‐to‐head construct to 86.2 kcal for a normal head‐to‐tail polymer construct (therefore, for the cleavage of a normal head‐to‐tail repeat unit, temperatures of approximately 450°C would be required). The thermodynamics of the unzipping, disproportionation, and back‐biting reactions in the resulting radical fragments were also investigated; the back‐biting process was found to require the least energy and provided the most stable radical fragment with a low probability for disproportionation or releasing of monomer to occur. The effect of solvation on the hydrogen‐bonding network in the acrylamide tetramer was studied by adding explicit molecules of water to the tetramer models. The addition of water had a significant effect on the stability of the model polymer slightly stabilizing the head‐to‐head polymer, and slightly destabilizing the head to tail polymer. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Luís Antônio Dantas Silva Fernanda Vieira Teixeira Raphael Caixeta Serpa Najla Locatelli Esteves Rayane Ramos dos Santos Eliana Martins Lima Marcílio Sérgio Soares da Cunha-Filho Adriano Antunes de Souza Araújo Stephânia Fleury Taveira Ricardo Neves Marreto 《Journal of Thermal Analysis and Calorimetry》2016,123(3):2337-2344