Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.
<p>Herein we
report a sulfur (IV) mediated cross-coupling for facile synthesis of heteroaromatic
substrates. Addition of heteroaryl nucleophiles onto a simple,
readily-accessible alkyl sulfinyl (IV) chloride allows formation of a trigonal
bipyramidal sulfurane intermediate. Reductive elimination therefrom provides bis-heteroaryl
products in a practical and efficient fashion. <br></p>
We have described simple, high-yield, protocols, which require only commonly accessible equipment, to synthesize a wide range of β-CD derivatives mono-substituted at the secondary face. These derivatives may be useful in their own right, and they are also scaffolds for further modification, and examples of the far broader array of derivatives that may be accessed by these procedures.
<a></a><a>Quantitative comparison of atomistic
simulations with experiment for glass-forming materials is made difficult by
the vast mismatch between computationally and experimentally accessible timescales.
Recently, we presented results for an epoxy network showing that the
computation of specific volume vs. temperature as a function of cooling rate in
conjunction with the time–temperature superposition principle (TTSP) enables
direct quantitative comparison of simulation with experiment. Here, we
follow-up and present results for the translational dynamics of the same
material over a temperature range from the rubbery to the glassy state. Using
TTSP, we obtain results for translational dynamics out to 10<sup>9</sup> s in
TTSP reduced time – a macroscopic timescale. Further, we show that the mean
squared displacement (MSD) trends of the network atoms can be collapsed onto a
master curve at a reference temperature. The computational master curve is
compared with the experimental master curve of the creep compliance for the
same network using literature data. We find that the temporal features of the
two data sets can be quantitatively compared providing an integrated view
relating molecular level dynamics to the macroscopic thermophysical
measurement. The time-shift factors needed for the superposition also show
excellent agreement with experiment further establishing the veracity of the
approach</a>.
