Anthracene congestion: 1,2,3-Tri(9-anthryl)benzene derivatives containing radially shaped π-clusters were constructed by using PdI-catalyzed Negishi coupling reactions. The presence of π-congestion as well as intermolecular π–π and CH–π interactions between anthracene units in the crystalline state gives these substances unique electronic properties. The excited-state dynamics associated with the radially
spectroscopy at low temperature, along with laser flash photolysis techniques at room temperature. The UV-vis spectrum of 31a was obtained by irradiating 1a-N2 in a 2-methyltetrahydrofuran matrix at 77 K. The ESR spectrum showed no triplet carbene signals, while a radical species was observed at the anticipated temperature of the decomposition of triplet carbene 31a. Transient absorption bands ascribable
Two enantiomers with helical carbon frameworks (M-HCFa and P-HCFa) and their conformational isomers (M-HCFb and P-HCFb) have been synthesized and characterized. The single-crystal analysis revealed the novel structures in which three propeller blades spiro-fused on two central benzene rings. The optical properties were further investigated, and stable bipolar electrochemiluminescence emissions were
Reaction of 1,3,5-tri-tert-butylbenzene with 2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione
作者:Kh. M. Nguen、V. K. Chaikovskii、V. D. Filimonov、A. A. Funk
DOI:10.1134/s107042801206005x
日期:2012.6
Reactions of 1,3,5-tri-tert-butylbenzene with 2,4,6,8-tetraiodo-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione in acetic and trifluoroacetic acids involve substitution of one or two tert-butyl groups in the aromatic ring with formation of mono-, di-, and triiodo-substituted derivatives. No iodo derivatives are formed in acetonitrile.
Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes
作者:Stojan Stavber、Petra Kralj、Marko Zupan
DOI:10.1055/s-2002-33339
日期:——
Benzene derivatives bearing at least one bulky alkyl group (i-Pr or t-Bu) were selectively and effectively iodinated using elemental iodine activated by 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor, F-TEDA-BF 4 ). Iodine atoms were progressively introduced at the most electron-rich and sterically less hindered position on the benzene ring. Not more than