- Molecular rods based on oligo-spiro-thioketals
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We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers.
- Wessig,Gerngro?,Freyse,Bruhns,Przezdziak,Schilde,Kelling
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p. 1125 - 1136
(2016/02/19)
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- Two flavors of PEPPSI-IPr: Activation and diffusion control in a single NHC-ligated Pd catalyst?
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Abnormal reactivity has been observed in Negishi, Suzuki-Miyaura, and Kumada-Tamao-Corriu cross-couplings in which PEPPSI-IPr (where PEPPSI stands for pyridine enhanced precatalyst preparation, stabilization, and initiation and IPr refers to the NHC ligand) is employed, implicating the presence of two distinct Pd0 species in the catalytic cycle. Polybrominated arenes and organometallic reagents react selectively to give the product of exhaustive polysubstitution regardless of the initial reaction stoichiometry. Competition experiments suggest that, after an initial activation controlled oxidative addition, reductive elimination produces an ultrareactive Pd0 species which consumes all remaining C-Br bonds in the molecule under diffusion control.
- Larrosa, Igor,Somoza, Clara,Banquy, Alexandre,Goldup, Stephen M.
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supporting information; experimental part
p. 146 - 149
(2011/03/20)
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- Palladium-catalyzed cross-coupling alkylation of arenediazonium o-benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides were reacted with tetramethyltin, tetrabutyltin or trialkylboranes. The reactions, carried out in the presence of palladium(II) derivatives as precatalysts, gave the methylation and alkylation products with good over
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 474 - 478
(2008/09/21)
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- New synthetic applications of indium organometallics in cross-coupling reactions
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The use of indium organometallics in multifold and sequential cross-coupling reactions is reported. Triorganoindium reagents (R3In) react, under palladium catalysis, with oligohaloarenes affording the multiple cross-coupling products in a single operation. In the reaction, the three organic groups (alkyl, aryl, alkenyl or alkynyl) attached to indium are efficiently transferred to the electrophile, with only a slight excess of organometallic reagent. We demonstrate that indium organometallics are useful reagents for sequential cross-coupling reactions. This reaction illustrates the high chemoselectivity of R3In. Georg Thieme Verlag Stuttgart.
- Pena, Miguel A.,Perez Sestelo, Jose,Sarandeses, Luis A.
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p. 485 - 492
(2007/10/03)
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- Tetraorganoindates as Nucleophilic Coupling Partners in Pd-Catalyzed Cross-Coupling Reactions
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(Equation presented) In situ generated ate complex In situ-generated tetraorganoindate complexes from the reaction of 1 equiv of indium trichloride with 4 equiv of appropriate organometallics are efficient nucleophiles in Pd-catalyzed cross-coupling reactions. In this novel reaction tetraorganoindates containing methyl, 1°- and 2°-alkyl, vinyl, alkynyl, and aryl groups transfer the four organic groups to a variety of electrophiles with high atom efficiency.
- Lee, Phil Ho,Lee, Sung Wook,Seomoon, Dong
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p. 4963 - 4966
(2007/10/03)
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- The preparations and some properties of mixed aryl-thienyl oligomers and polymers
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The syntheses by transition metal coupling reactions of a large number of oligomers constructed from benzene and thiophene rings are described. The first use of arylcadmium chlorides for such coupling reactions is reported. The routes chosen allow for rational variation in the modes of linkage, the substitution and the proportions of the two units. The benzene and thiophene rings are always joined in a known order and may bear a wide variety of regularly spaced functional groups. Additionally the shape of the oligomers may be varied at will. In all cases p-type doping with iodine or ferric chloride leads to large enhancements in conductivity.
- Pelter, Andrew,Jenkins, Ieuan,Jones, D. Elfyn
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p. 10357 - 10400
(2007/10/03)
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- SYNTHESIS AND SPECTROSCOPY OF 1,4-DIALKYLBENZENES
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Five linear 1,3-dialkylbenzenes namely, dibutyl-, dipentyl-, dihexyl-, diheptyl- and dioctylbenzenes were prepared in good yield via two simple catalytic routes under very mild conditions and affording insignificant side products, The starting feed, 1,4-d
- Issac, Yvette A.,El-Zein, S. M.,Barakat, Y.
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p. 463 - 470
(2007/10/02)
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- Cyclophanes, XXI. The Chemical Behavior of Paracyclophane: Reactions of the Benzene Ring
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Preparative quantities of paracyclophane (1b) may be prepared from paracyclophane-3,6-dione (9) by Wolff-Kishner reduction.After a detailed dicussion of the 1H and 13C NMR spectra of 1b, its behavior in substitution and addition reactions is describ
- Noble, Karl-Ludwig,Hopf, Henning,Ernst, Ludger
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p. 455 - 473
(2007/10/02)
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- Photoelectron Spectra of Paracyclophane and Paracyclophane-4-ene. An Estimation of Inductive and Hyperconjugative Effect for Paracyclophanes
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Based on the split of the first two bands in the photoelectron(PE)spectra of paracyclophane, paracyclophane-4-ene, 1,4-di-n-butyl-, 1,4-di-n-propyl- and 1,4-diethylbenzene as well as p-xylene it is shown that the inductive and hyperconjugative effec
- Gleiter, Rolf,Hopf, Henning,Eckert-Maksic, Mirjana,Noble, Karl-Ludwig
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p. 3401 - 3403
(2007/10/02)
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