- Ruthenium-catalyzed knoevenagel condensation: A new route toward cyano-substituted poly(p-phenylenevinylene)s
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The ruthenium-catalyzed Knoevenagel reaction was developed for the preparation of cyano-substituted conjugated polymers. The polymerization was quenched by pouring the reaction mixture into methanol. The structures of polymers were confirmed by spectroscopic studies and elemental analysis. The results show that Knoevenagel polycondensation mediated by transition metal complexes enjoys the advantages of neutral and mild reaction conditions.
- Liao, Jian,Wang, Qing
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- Photochemical Synthesis of Carbon-14 Labelled Dibenzanthracene
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Carrier-free dibenzanthracene (DBA,12*) has been prepared for the first time using methyl iodide as the source of the label.The key step in this radiosynthesis consisted of the regiospecific photocyclization of 2',5'-divinyl-1,1':4',1''-terphenyl 10* to 5,6,12,13-tetrahydro-DBA 11* followed by dehydrogenation to 12* with DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone).Divinylterphenyl 10* was obtained from 2',5'-bis(bromomethyl)-1,1':4',1''-terphenyl 3 via the diformyl derivative 9 and its Wittig olefination with the triphenylphosphonium salt of14CH3I.Thus 12* was synthesized with a radiochemical purity exceeding 99percent.The chemical yield amounted to 58percent from 9 in the case of 12* with a specific activity of 391 MBq mmol-1 and to 12percent in the case of carrier-free 12* with a specific activity of 4.14 GBq mmol-1.Wide applicability of this radiosynthetic approach to the preparation of many other carbon-14 labelled polycyclic aromatic hydrocarbons can be envisaged.
- Platt, Karl L.,Setiabudi, Frans
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p. 2005 - 2010
(2007/10/02)
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