29421-92-9Relevant articles and documents
Synthesis of Trisubstituted Thiophenes via a Halogen Dance Reaction at 2-Bromo-5-methylthiophene
Froehlich,Hametner,Kalt
, p. 325 - 330 (1996)
A new example of a selective halogen dance reaction was observed upon lithiation of 2-bromo-5-methylthiophene with LDA under appropriate reaction conditions. A series of 2-substituted 3-bromo-5-methylthiophenes was prepared by reacting the thus selectively generated intermediate 3-bromo-2-lithio-5-methylthiophene with various electrophiles to study scope and limitations of the reaction.
The catalytic behavior of heterocenes activated by TIBA and MMAO under a low Al/Zr ratios in 1-octene polymerization
Nifant'ev, Ilya E.,Vinogradov, Alexander A.,Vinogradov, Alexey A.,Churakov, Andrei V.,Bagrov, Vladimir V.,Kashulin, Igor A.,Roznyatovsky, Vitaly A.,Grishin, Yury K.,Ivchenko, Pavel V.
, p. 12 - 24 (2019/01/03)
A series of SiMe2-bridged ansa-zirconocenes LZrCl2 derived from heterocyclic ligands such as cyclopenta[1,2-b:4,3-b’]dithiophene, 5,6-dihydroindeno[2,1-b]indole and 5,10-dihydroindeno[1,2-b]indole, called “heterocenes” were synthesized and characterized by NMR spectroscopy and by X-ray diffraction analysis. These complexes were activated by triisobutylaluminium (TIBA) at AlTIBA/Zr ratio ～75 and then by MMАO-12 at AlMAO/Zr ratio ～10, and were studied in the polymerization of 1-octene in the absence or presence of molecular hydrogen. In the absence of molecular hydrogen, derivatives of cyclopenta[1,2-b:4,3-b’]dithiophene and dihydroindeno[2,1-b]indole demonstrated high catalytic activity, while dihydroindeno[1,2-b]indole complexes catalyzed slow polymerization with the formation of ultrahigh molecular weight poly(1-octene)s. In the presence of molecular hydrogen, derivatives of dihydroindeno[1,2-b]indole showed an order of magnitude increase in the catalytic activity. β-Hydride elimination, β-hexyl elimination and Zr-Al transfer were detected as the main chain release mechanisms depending on the nature of the ligand used. A novel chain termination with selective formation of –C(Me)=CHCH2– unsaturations was detected. It was found that heterocenes maintained a high catalytic activity up to 120 °C. Due to their high thermal stability and good hydrogen response, heterocenes are promising catalysts for the oligomerization and hydrooligomerization of α-olefins in the production of high-quality motor oil base stocks.
1,3-bicyclo[1.1.1]pentanediyl: The shortest rigid linear connector of phenylated photochromic units and a 1,5-dimethoxy-9,10-di(phenylethynyl) anthracene fluorophore
De Meijere, Armin,Ligang, Zhao,Belov, Vladimir N.,Bossi, Mariano,Noltemeyer, Matthias,Hell, Stefan W.
, p. 2503 - 2516 (2008/04/01)
An excess of bis-1,3-(4-iodophenyl)bicyclo[1.1.1]pentane, prepared in 63% yield by iodination of 1.3-diphenylbicyclo[1.1.1]pentane, was selectively mono-coupled with 9-ethynyl-1,5-dimethoxy-10-phenylethynylanthracene (26), and subsequently with the zinc derivatives of 1-(2-methyl/methoxy-4-methyl-5- phenylthiophen-3-yl)-2-(2-methyl/methoxy-4-methylthiophen-3-yl) perfluorocyclopentenes (38-H-41-H). Regioselective synthesis of the 2-unsubslituted thiophenes 38-H-41-H required intermediate prepara tion of 2-trimethylsilyl-3,5-dimethyl-4-bromothiophene (37) or 2-trimethylsilyl-5- methoxy-3-methyl-4-bromothiophene (40). Protection of the α-position of the thiophene ring with a 2-trimethylsilyl group blocks the rearrangement of the 4-lithio derivatives into the corresponding 2-lithiated thiophenes. With the bicyclo[1.1.1]pentane frag ment linking the photochromic units 1-3 and 1,5-dimethoxy-9,10-di(phenylethynyl)anthracene as a fluorescent part, quantitative resonance energy transfer between the excited state of the fluorophore (donor) and the closed form of the photochromic units 1-3 (acceptors) was observed. The closed forms of the methoxy-substituted photochromic units 2 and 3 are less resistant to UV light (313 nm) than the closed form of 1.
