Thiourea-Catalyzed C−F Bond Activation: Amination of Benzylic Fluorides

We describe the first thiourea-catalyzed C−F bond activation. The use of a thiourea catalyst and Ti(OiPr)₄ as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.     

Pd2(dba)3/Xantphos-catalyzed cross-coupling of thiols and aryl bromides/triflates

The cross-coupling of aliphatic and aromatic thiols and aryl bromides/triflates mediated by a Pd₂(dba)₃/Xantphos catalytic system in refluxing xylene (140 °C) affords the corresponding aryl thioethers in good to excellent yields.     

Characterization of major and minor alk(en)ylresorcinols from mango (Mangifera indica L.) peels by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

5-Alkyl- and 5-alkenylresorcinols, as well as their hydroxylated derivatives, were extracted from mango (Mangifera indica L.) peels, purified on polyamide and characterized by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APcI-MS) for the first time. Among the 15 compounds analyzed, 3 major and 12 minor C(15)-, C(17)-, and C(19)-substituted resorcinols and related analogues, showing varying degrees of unsaturation, were characterized by their specific fragmentation patterns in collision-induced dissociation experiments. This marks the first report on the occurrence of mono-, di-, and triunsaturated C(15)-homologues, saturated and triunsaturated C(17)-homologues, and mono- and diunsaturated C(19)-homologues in mango peels. Additionally, several hydroxylated C(15)- and C(17)-homologues, also not yet described in mango, and a C(14)-monoene, unique because of its even-numbered side chain, were tentatively identified on the basis of their fragmentation patterns. The results obtained in the present study indicate that HPLC-DAD-APcI-MS(n), combined with the newly developed solid-phase extraction, is a powerful tool for the analysis of alk(en)ylresorcinols and could therefore be used for their determination in various matrices.     

Alterations of the exo- and endometabolite profiles in breast cancer cell lines: A mass spectrometry-based metabolomics approach

In recent years, knowledge about metabolite changes which are characteristic for the physiologic state of cancer cells has been acquired by liquid chromatography coupled to mass spectrometry. Distinct molecularly characterized breast cancer cell lines provide an unbiased and standardized in vitro tumor model reflecting the heterogeneity of the disease. Tandem mass spectrometry is a widely applied analytical platform and highly sensitive technique for analysis of complex biological samples. Endo- and exometabolite analysis of the breast cancer cell lines MDA-MB-231, -453 and BT-474 as well as the breast epithelial cell line MCF-10A has been performed using two different analytical platforms: UPLC-ESI-Q-TOF based on a scheduled precursor list has been applied for highlighting of significant differences between cell lines and HPLC-ESI-QqQ using multiple reaction monitoring has been utilized for a targeted approach focusing on RNA metabolism and interconnected pathways, respectively. Statistical analysis enabled a clear discrimination of the breast epithelial from the breast cancer cell lines. As an effect of oxidative stress, a decreased GSH/GSSG ratio has been detected in breast cancer cell lines. The triple negative breast cancer cell line MDA-MB-231 showed an elevation in nicotinamide, 1-ribosyl-nicotinamide and NAD+ reflecting the increased energy demand in triple negative breast cancer, which has a more aggressive clinical course than other forms of breast cancer. Obtained distinct metabolite pattern could be correlated with distinct molecular characteristics of breast cancer cells. Results and methodology of this preliminary in vitro study could be transferred to in vivo studies with breast cancer patients.     

Resolvent Estimates and Matrix-Valued Schrödinger Operator with Eigenvalue Crossings; Application to Strichartz Estimates

We consider a semi-classical Schrödinger operator with a matrix-valued potential presenting eigenvalue crossings on isolated points. We obtain estimates for the boundary values of the resolvent under a generalized non-trapping assumption. As a consequence, we prove the smoothing effect of this operator, derive Strichartz type estimate for the propagator and get an existence theorem for a system of non-linear Schrödinger equations.     

Superoxide dismutase-like activity of cobalt(II) complexes based on a sugar platform

A SOD-like activity evaluated by a modified McCord-Fridovich test was evidenced for two Co(II) complexes built from "glycoligands" using a sugar platform derived from d-galactose and D-galactal and functionalized by three 2-picolyl groups.     

Recent Applications of Molecular Spectroscopy in Bioorganometallic Chemistry–Part 2: Ferrocenes and Other Organometallic Complexes

Abstract: This is the second part of an overview of the applications of the various molecular spectroscopic methods that have been employed in bioorganometallic chemistry research since 2005 focusing on ferrocenes and other non-metal carbonyl organometallic complexes. These spectroscopic methods encompass infrared (IR), nuclear magnetic resonance (NMR), mass, Raman, ultraviolet-visible (UV-Vis), and several other less common spectroscopic techniques.