- Opening or closing the lock? when reactivity is the key to biological activity
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Thiol-mediated processes play a key role to induce or inhibit inflammation proteins. Tailoring the reactivity of electrophiles can enhance the selectivity to address only certain surface cysteines. Fourteen 2',3,4,4'- tetramethoxychalcones with different α-X substituents (X=H, F, Cl, Br, I, CN, Me, p-NO2-C6H4, Ph, p-OMe-C 6H4, NO2, CF3, COOEt, COOH) were synthesized, containing the potentially electrophilic α,β-unsaturated carbonyl unit. The assessment of their reactivity as electrophiles in thia-Michael additions with cysteamine shows a change in the reactivity of more than six orders of magnitude. Moreover, a clear correlation between their reactivity and an influence on the inflammation proteins heme oxygenase-1 (HO-1) and the inducible NO synthase (iNOS) is demonstrated. As the biologically most active compound, the α-CF3-chalcone is shown to inhibit the NO production in RAW264.7 mouse macrophages in the nanomolar range. More than a million by only one substituent: The direct manipulation of the chemical reactivity of electrophilic agents could be proven for chalcones by simply exchanging the α-hydrogen atom of the α,β-unsaturated carbonyl unit with different substituents (X), leading to a change in reactivity of more than six orders of magnitude for thia-Michael additions with cysteamine, which correlates very well with two electrophile-sensitive biological readouts (see scheme).
- Al-Rifai, Nafisah,Ruecker, Hannelore,Amslinger, Sabine
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supporting information
p. 15384 - 15395
(2013/11/06)
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- Diazoaldehyde Chemistry: Part 4 - Vilsmeier-Haack Formylation of Diazo Compounds: A Re-investigation
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Diazomethyl ketones (2-diazoethanones) were reacted with the Vilsmeier reagent ((chloromethylidene)dimethylammonium chloride) to yield α-diazo-β-oxoaldehydes and chloromethyl ketones. 2′,4′-Dimethoxy-α-diazoacetophenone gave 2-chloro-1-(2,4-dimethoxyphenyl)-3-(dimethylamino)prop-2-en-1-one (5) in addition to the expected products. Phenyldiazomethanes gave the corresponding benzyl chlorides but not the (phenyl)diazoacetaldehydes even at temperatures as low as -60°. The diazo-transfer reactions of phenylacetaldehydes and 2-azido-1-ethylpyridin-1-ium tetrafluoroborate also did not yield the expected(phenyl)diazoacetaldehydes.
- Sezer, Oezkan,Dabak, Kadir,Anac, Olcay,Akar, Ahmet
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p. 960 - 965
(2007/10/03)
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- The Chemistry of Nitrilium Salts. Part 1. Acylation of Phenols and Phenol Ethers with Nitriles and Trifluoromethanesulphonic Acid
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Aliphatic nitriles, RCN (R = Me, n-Pr, CH2Cl, and CCl3), in the presence of trifluoromethanesulphonic acid have been found to react with a number of mono-, di-, and tri-substituted phenols and phenol ethers at room temperature to give ketones after hydrolysis of the reaction mixture.Moderate to good yields of acylation products are obtained in the majority of these reactions.The yield with malononitrile and succinonitrile, which are only slightly soluble in the reaction medium, are generally poor, and reaction involves only one of the available nitrile groups.Attempts to use diethyl ether and dichloromethane as solvents for some of these reactions were unsuccessful, but limited success was achieved with nitromethane.
- Booth, Brian L.,Noori, Ghazi F.M.
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p. 2894 - 2900
(2007/10/02)
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