In: Journal of Organic Chemistry, 2011, vol. 75, no. 24, p. 8363–8371
Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H₂O, DMSO, 110 °C) to give the desired compounds in 19−84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously...
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In: Journal of Physical Organic Chemistry, 2012, p. -
Variable temperature ¹H NMR spectroscopic studies of 2, 6-di(o-anisyl) anisole show syn and anti atropisomers at low temperature. The barrier for interconverting these isomers by rotation about the aryl-aryl bond, found by fitting the experimental data, is 41.2 kJ/mol.
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In: Chemistry - A European Journal, 2009, vol. 15, no. 7, p. 1604 - 1617
Low-energy electronic transitions have been detected spectroscopically in the FeII-FeIII mixed-valent biferrocenyl radical cation, but are absent in the spectra of the neutral analogue. They have been assigned by time-dependent DFT calculations (squares in figure). Analogous investigations were performed for the bisfulvalenide FeII-FeIII radical cation....
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In: Journal of the American Chemical Society, 2007, vol. 129, no. 26, p. 8380-8388
p-Biphenylyl, o-biphenylyl, and 1-naphthyl azides were deposited in argon at low temperature in the presence and absence of HCl. In the absence of HCl, the known electronic and vibrational spectra of the corresponding triplet nitrenes, azirines, and didehydroazepines were observed, whereas in the presence of HCl, photolysis of these azides produces new electronic spectra assigned to...
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In: Journal of the American Chemical Society, 2014, vol. 136, no. 37, p. 12832–12835
Macrocyclizations in exceptionally good yields were observed during the self-condensation of N-benzylated phenyl p-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. An ortho-alkyloxy side chain on the N-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this...
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In: Photochemical & Photobiological Sciences, 2012, vol. 11, no. 3, p. 548-555
Quantum yields for the photoinduced release of seven different commonly used leaving groups (LGs) from the o-nitroveratryl protecting group were measured. It was found that these quantum yields depend strongly on the nature of the LGs. We show that the quantum efficiency with which the LGs are released correlates with the stabilization that these LGs provide to o-nitrobenzyl-type radicals because...
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In: Chemistry – A European Journal, 2014, vol. 20, no. 26, p. 8062–8067
The quantum yield for the release of leaving groups from o-nitrobenzyl “caged” compounds varies greatly with the nature of these leaving groups, for reasons that have never been well understood. We found that the barriers for the primary hydrogen-atom transfer step and the efficient nonradiative processes on the excited singlet and triplet surfaces determine the quantum yields. The...
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In: Chemistry, a European Journal, 2010, vol. 16, no. 24, p. 7121–7124
In contrast to the structurally and configurationally stable alkyl- or aryl-substituted cyclopropyl radical cations, cyclopropyl silyl ethers undergo spontaneous ring opening upon oxidation whereby the endocyclic C-C(O-TMS) bond is cleaved with remarkable selectivity. DFT calculations on 1-trimethylsilyloxybicyclo[4.1.0]heptane show that this selectivity arises from the topology of the potential...
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In: Inorganic Chemistry, 2009, vol. 48, no. 9, p. 4075–4082
To elucidate the multifaceted but poorly understood chemistry of the pivotal polysulfur−nitrogen heterocycle, tetrasulfur tetranitride (S₄N₄, 1), its photochemistry was studied in Ar matrices. Thereby two primary intermediates and a secondary one (2−4) were detected, and their UV−vis and IR spectra were identified through specific interconversions of...
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In: Physical Chemistry Chemical Physics, 2006, vol. 8, p. 719-727
The photochemistry of p-azidoaniline was studied in argon matrices in the absence and presence of oxygen. With the help of quantum chemical calculations we were able to characterize the triplet p-aminophenylnitrene as well as the cis- and trans-p-aminophenylnitroso oxides. It was found that the latter two isomers can be interconverted by selective...
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