The Schlenk equilibrium involving RMgX, R2Mg, and MgX2 (R = Me, Et, Ph and X = Cl, Br) has been
studied both in the gas phase and in diethyl ether (Et2O) and tetrahydrofuran (THF) solutions by means of
the density functional theory (DFT) B3LYP/6-31+G* method. Solvation was modeled using the supermolecule
approach. The stabilization due to interaction with solvent molecules decreases in the order MgX2 > RMgX
> R2Mg and among the groups (R and X) Ph > Me > Et and Cl > Br. Studied magnesium compounds are
more strongly solvated by THF compared to Et2O. The magnesium halide is solvated with up to four solvent
molecules in THF solution, assuming that trans-dihalotetrakis(tetrahydrofurano)magnesium(II) complex forms.
The formation of cis-dihalotetrakis(tetrahydrofurano)magnesium(II) is energetically less favorable than the
formation of corresponding disolvated complexes. The predominant species in the Schlenk equilibrium are
RMgX in Et2O and R2Mg + MgX2 in THF, which is consistent with experimental data.
The copper-free Sonogashira cross-coupling reaction consisting of oxidative addition, cisÀtrans isomerization, deprotonation, and reductive elimination was computationally modeled using the DFT B97D/cc-pVDZ method for reaction between phenyl bromide and phenylacetylene. Tetrakis(triphenylphosphano)palladium was used as a catalyst and sec-butylamine as a base. The reaction mechanism was studied in dichloromethane solution. Oxidative addition proceeds through the biligated pathway, and the catalytically active palladium species is Pd(PPh 3 ) 3 . Amines, present in the reaction mixture, can inhibit oxidative addition by coordinating to Pd(PPh 3 ) 3 .' ASSOCIATED CONTENT b S Supporting Information. Geometries and energies for all discussed structures are deposited. This material is available free of charge via the Internet at http://pubs.acs.org.
The glial cell line-derived neurotrophic
factor (GDNF) family ligands (GFLs) support the survival and functioning
of various neuronal populations. Thus, they could be attractive therapeutic
agents against a multitude of neurodegenerative diseases caused by
progressive death of GFLs responsive neurons. Small-molecule ligands
BT13 and BT18 show an effect on GDNF family receptor GFRα1 and
RET receptor tyrosine kinase RetA function. Thus, their potential
binding sites and interactions were explored in the GDNF–GFRα1–RetA
complex using molecular docking calculations as well as molecular
dynamics (MD) simulations. Three possible regions were examined: the
interface between GDNF and GFRα1 (region A), the RetA interface
with GFRα1 (region B), and a possible allosteric site in GFRα1
(region C). The results obtained by the docking calculations and the
MD simulations indicate that the preferable binding occurs at the
allosteric site. A less preferable binding site was detected on the
RetA surface interfacing GFRα1. In the membrane-bound state
of RetA this can enable compounds BT13 and BT18 to act as direct RetA
agonists. The analysis of the MD simulations shows hydrogen bonds
for BT13 and significant hydrophobic interactions with GFRα1
for BT13 and BT18 at the allosteric site.
Mechanism of an efficient and easily applicable catalytic system for the copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) reaction, consisting of phosphane‐ligated CuI carboxylates and apolar/aprotic solvent was investigated by means of 1H NMR reaction monitoring techniques, isotope exchange studies, and DFT calculations (at the M06L/6‐311++G(d,p)//B97D/cc‐pVDZ (SDD) level of theory). Kinetic analysis indicates 1st order kinetics with respect to [Azide] and nonlinear positive order in [Cu]. H/D scrambling between alkynes reveals a quickly reached equilibrium existing between CuI–carboxylates and CuI–acetylides and that proton transfer processes are mediated by acetate/acetic acid system. According to the computational results, the Cu–triazolide forms a dinuclear structure that equalizes the copper atoms in the catalytic complex.
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