Triflic Acid-Mediated Condensation of Phthalimide with Diaryl Ethers as a Route to Spiro-Isoindolinones: Mechanistic Insights and Related Reactions.

Phthalimide and -phenylphthalimide smoothly condense with di--tolyl ether in triflic acid (CFSOH, TfOH) to obtain the corresponding spiro[isoindoline-1,9'-xanthen]-3-ones. Structural analogs of phthalimide, such as phthalic anhydride and 1,3-indandione (but not saccharin), show similar reactivity. In contrast, N-(tetrafluoropyridin-4-yl)phthalimide reacts with DTE by an alternative pathway, yielding isobenzofuran dispiro derivative.

Redox Transformations of the OX063 Radical in Biological Media: Oxidative Decay of Initial Trityl with Further Formation of Structurally-Modified TAM.

Being a low-toxic and hydrophilic representative of TAM, OX063 has shown its suitability for in-vivo and in-cell EPR experiments and design of spin labels. Using C labeling, we investigated the course of oxidative degradation of OX063 into quinone-methide (QM) under the influence of superoxide as well as further thiol-promoted reduction of QM into TAM radical, which formally corresponds to substitution of a carboxyl function by a hydroxyl group. We found these transformations being quantitative in model reactions mimicking specific features of biological media and confirmed the presence of these reactions in the blood and liver homogenate of mice in vitro.

From a humorous post to a detailed quantum-chemical study: isocyanate synthesis revisited.

Isocyanates play an essential role in modern manufacturing processes, especially in polyurethane production. There are numerous synthesis strategies for isocyanates both under industrial and laboratory conditions, which do not prevent searching for alternative highly efficient synthetic protocols. Here, we report a detailed theoretical investigation of the mechanism of sulfur dioxide-catalyzed rearrangement of phenylnitrile oxide into phenyl isocyanate, which was first reported in 1977.

F electron nuclear double resonance (ENDOR) spectroscopy for distance measurements using trityl spin labels in DNA duplexes.

The combination of fluorine labeling and pulsed electron-nuclear double resonance (ENDOR) is emerging as a powerful technique for obtaining structural information about proteins and nucleic acids. In this work, we explored the capability of Mims F ENDOR experiments on reporting intermolecular distances in trityl- and F-labeled DNA duplexes at three electron paramagnetic resonance (EPR) frequencies (34, 94, and 263 GHz). For spin labeling, we used the hydrophobic Finland trityl radical and hydrophilic OX063 trityl radical.

Synthesis of Nitro- and Acetyl Derivatives of 3,7,10-Trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane.

Here, we report the study results of the nitration of 3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane (THAP) by different nitrating agents such as nitric acid, mixed nitric/sulfuric acids, nitric anhydride, and mixed concentrated nitric acid/acetic anhydride to furnish 3,7,10-trioxo-2-nitro-2,4,6,8,9,11-hexaaza[3.