15 research outputs found
Synthetic and computational studies on the tricarboxylate core of 6,7-dideoxysqualestatin H5 involving a carbonyl ylide cycloaddition–rearrangement
Reaction of diazodiketoesters 17 and 28 with methyl glyoxylate in the presence of catalytic rhodium(II) acetate generates predominantly the 6,8-dioxabicyclo[3.2.1]octanes 29 and 30, respectively. Acid-catalysed rearrangement of the corresponding alcohol 31 favours, at equilibrium, the 2,8-dioxabicyclo[3.2.1]octane skeleton 33 of the squalestatins–zaragozic acids. Force field calculations on the position of the equilibrium gave misleading results. DFT calculations were correct in suggesting that the energy difference between 31 and 33 should be small, but did not always suggest the right major product. Calculation of the NMR spectra of the similar structures could be used to assign the isomers with a high level of confidence
Comparison of thermal effects of stilbenoid analogs in lipid bilayers using differential scanning calorimetry and molecular dynamics: correlation of thermal effects and topographical position with antioxidant activity
In previous studies it was shown that cannabinoids (CBs) bearing a phenolic hydroxyl group modify the
thermal properties of lipid bilayers more significantly than
methylated congeners. These distinct differential properties
were attributed to the fact that phenolic hydroxyl groups
constitute an anchoring group in the vicinity of the headgroup, while the methylated analogs are embedded deeper
towards the hydrophobic region of the lipid bilayers. In this
work the thermal effects of synthetic polyphenolic stilbenoid analogs and their methylated congeners have been
studied using differential scanning calorimetry (DSC).Molecular dynamics (MD) simulations have been performed to explain the DSC results. Thus, two of their
phenolic hydroxyl groups orient in the lipid bilayers in
such a way that they anchor in the region of the headgroup. In contrast, their methoxy congeners cannot anchor
effectively and are embedded deeper in the hydrophobic
segment of the lipid bilayers. The MD results explain the
fact that hydroxystilbenoid analogs exert more significant
effects on the pretransition than their methoxy congeners,
especially at low concentrations. To maximize the polar
interactions, the two phenolic hydroxyl groups are localized in the vicinity of the head-group region, directing the
remaining hydroxy group in the hydrophobic region. This
topographical position of stilbenoid analogs forms a mismatch that explains the significant broadening of the width
of the phase transition and lowering of the main phasetransition temperature in the lipid bilayers. At high concentrations, hydroxy and nonhydroxy analogs appear to
form different domains. The correlation of thermal effects
with antioxidant activity is discusse
A clean, palladium-catalyzed oxidative esterification of aldehydes using benzyl chloride
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Selective catalytic carbanionic ethylation of methylphenols: influence of catalyst and substitution pattern
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Dendrimers as biopharmaceuticals: synthesis and properties
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Transition metal complexes of new glyoxylato-aroylhydrazones and their role in l-ascorbic acid oxidation inhibition
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New stable, isolable triarylmethyl based dyes absorbing in the near infrared
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Selectivity in the cycloadditions of carbonyl ylides with glyoxylates: an approach to the zaragozic acids—squalestatins
Reaction of diazodiketoester 8 with glyoxylates in the presence of catalytic rhodium(n) acetate generates 6,8-dioxabicyclo[3.2.1]octanes 9 and 11 in good yield. Elaboration of 9 provides a suitable alcohol 25 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 26 of the zaragozic acids-squalestatins. More substituted diazodiketoesters 36 and 40 also undergo highly regio- and diastereoselective cycloaddition with glyoxylates to give the cycloadducts 41,43 and 44. © The Royal Society of Chemistry 2000
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Compounds that modulates AMPA receptor function
The invention provides compounds of the formula (I): (I) wherein A1, A2, R2, R4, B1, B2, X, X1, n, a and b are as defined are defined in the specification, to pharmaceutical compositions comprising the compounds and the compounds for use as medicaments. The compounds potentiate AMPA receptor function and are expected to be useful in the treatment of central nervous system disorders, for example in the treatment of depressive disorders, mood disorders and cognitive dysfunction associated with neuropsychiatric disorders such as schizophrenia
Microwave assisted solid additive effects in simple dry chlorination reactions with n-chlorosuccinimide
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