In: The Journal of Organic Chemistry, 2013, vol. 78, no. 7, p. 2908–2913
Parent cyclobutenedione 1 was photolyzed and ionized in an Ar matrix at 10K. The bisketene 2 that results in both cases (in the form of its radical cation after ionization) was characterized by its IR spectrum and by high-level quantum chemical calculations. Experiment and theory show that the neutral bisketene has only a single conformation where the two ketene moieties are nearly perpendicular,...
|
In: The Journal of Physical Chemistry, 2012, vol. 116, no. 41, p. 10203–10208
High-level G3X(MP2)-RAD calculations have been carried out to examine the effect of interposing a “connector” group (W) on the interaction between a substituent (X) and the radical center in carbon-centered radicals (•CH₂–W–X). The connector groups include −CH₂–, −CH═CH–, −C≡C–, −p-C₆H₄–, −m-C₆H₄–, and −o-C₆H₄–,...
|
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.
|
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...
|
In: The Journal of Organic Chemistry, 2011, vol. 76, no. 12, p. 4818–4830
The performance of 250 different computational protocols (combinations of density functionals, basis sets and methods) was assessed on a set of 165 well-established experimental ¹H–¹H nuclear coupling constants (JH–H) from 65 molecules spanning a wide range of “chemical space”. Thereby we found that, if one uses core-augmented basis sets and allows for linear scaling...
|
In: The Journal of Physical Chemistry A, 2011, vol. 115, no. 26, p. 7700–7708
Extending our previous study on the title species (J. Phys. Chem. A2010, 114, 6787), we investigated the dimer cations that are formed on oxidation of the glucobrassin derivatives indole-3-carbinol (I3C) and diindolylmethane (DIM) and of parent indole (I). Radiolysis in ionic liquid and Ar matrices shows that, at sufficiently high concentrations and/or on...
|
In: Organic & Biomolecular Chemistry, 2011, vol. 9, p. 3636-3657
The bond dissociation energies (BDEs) and radical stabilization energies (RSEs) which result from 166 reactions that lead to carbon-centered radicals of the type ˙CH₂X, ˙CHXY and ˙CXYZ, where X, Y and Z are any of the fourteen substituents H, F, Cl, NH₂, OH, SH, CH=CH₂, C≡CH, BH₂, CHO, COOH, CN, CH₃, and CF₃, were calculated using spin-restricted and -unrestricted variants of the...
|
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...
|
In: Journal of the American Chemical Society, 2010, vol. 132, no. 41, p. 14649–14660
The [1.1.1]propellane radical cation 1•+, generated by radiolytic oxidation of the parent compound in argon and Freon matrices at low temperatures, undergoes a spontaneous rearrangement to form the distonic 1,1-dimethyleneallene (or 2-vinylideneallyl) radical cation 3•+ consisting of an allyl radical substituted at the 2-position by a vinyl...
|
In: The Journal of Physical Chemistry A, 2010, vol. 114, no. 25, p. 6787–6794
The primary products, i.e., the radical cations and radicals obtained on oxidation of the glucobrassicin metabolites (and dietary supplements), indole-3-carbinol (I3C) and diindolylmethane (DIM), and those from parent indole (I) are characterized in an ionic liquid and in Ar matrices. The radical cations of I and I3C are stable toward (photo)deprotonation under these conditions, but the resulting...
|
