- Redox-Neutral Selenium-Catalysed Isomerisation of para-Hydroxamic Acids into para-Aminophenols
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A selenium-catalysed para-hydroxylation of N-aryl-hydroxamic acids is reported. Mechanistically, the reaction comprises an N?O bond cleavage and consecutive selenium-induced [2,3]-rearrangement to deliver para-hydroxyaniline derivatives. The mechanism is studied through both 18O-crossover experiments as well as quantum chemical calculations. This redox-neutral transformation provides an unconventional synthetic approach to para-aminophenols.
- Chuang, Hsiang-Yu,Schupp, Manuel,Meyrelles, Ricardo,Maryasin, Boris,Maulide, Nuno
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p. 13778 - 13782
(2021/03/31)
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- DPPH radical scavenging activity of paracetamol analogues
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Biochemical studies suggest a direct relationship between the radical scavenging activity of paracetamol (I) and its antipyretic and analgesic action. To evaluate the effect of chemical modifications on the radical scavenging activity of compounds of type I, analogues 1-14 were prepared and submitted to a stable free radical (DPPH; 1,1-diphenyl-2-picryl-hydrazyl) assay. All paracetamol derivatives showed a significant higher efficiency than the parent compound. This study showed that radical scavenging activity can be increased by decreasing the phenolic ortho substituents steric hindrance or by introducing substituents on the acyl moiety like an indazole ring or the ionic N-methyl morpholinium group. A significant activating effect was also observed by replacing the 1,4-acylamidophenol with a 1,4-acylamidonaphthol system.
- Alisi, Maria Alessandra,Brufani, Mario,Cazzolla, Nicola,Ceccacci, Francesca,Dragone, Patrizia,Felici, Marco,Furlotti, Guido,Garofalo, Barbara,La Bella, Angela,Lanzalunga, Osvaldo,Leonelli, Francesca,Marini Bettolo, Rinaldo,Maugeri, Caterina,Migneco, Luisa Maria,Russo, Vincenzo
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p. 10180 - 10187
(2013/01/15)
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- INVERSE AGONISTS AND NEUTRAL ANTAGONISTS FOR THE TSH RECEPTOR
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TSHR inverse agonists and neutral antagonists that are useful for treating Graves' orbitopathy, Graves' hyperthyroidism and/or thyroid cancer.
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Page/Page column 53-55
(2011/10/31)
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- Aryldiazonium Salts as Photo-affinity Labelling Reagents for Proteins
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Aryldiazonium tetrafluoroborates, substituted in the para-position by electron donating substituents, are potential photo-affinity labelling reagents for proteins and after light activation irreversibly inhibit acetylcholinesterase; using radiolabelled reagent, the inactivation is shown to be approximately stoicheiometric.
- Kieffer, Brigitte L.,Goeldner, Maurice Ph.,Hirth, Christian G.
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p. 398 - 399
(2007/10/02)
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- Studies on the mechanism of toxicity of acetaminophen. Synthesis and reactions of N-acetyl-2,6-dimethyl- and N-acetyl-3,5-dimethyl-p-benzoquinone imines
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N-Acetyl-2,6-dimethyl-p-benzoquinone imine and N-acetyl-3,5-dimethyl-p-benzoquinone imine were prepared from 2,6-dimethylacetaminophen and 3,5-dimethylacetaminophen by oxidation with lead tetraacetate. Reaction of N-acetyl-2,6-dimethyl-p-benzoquinone imine with hydrochloric acid gave 3'-chloro-2',6'-dimethyl-4'-hydroxyacetanilide, whereas ethanethiol, aniline, and ethanol gave tetrahedral adducts resulting from addition to the imine carbon. Water gave 2,6-dimethyl-p-benzoquinone. With N-acetyl-3,5-dimethyl-p-benzoquinone imine, water and aniline gave substitution on the imine carbon, yielding 2,6-dimethyl-p-benzoquinone and 3,5-dimethyl-N-phenyl-p-benzoquinone imine, respectively. Ethanethiol gave 3',5'-dimethyl-2'-(ethylthio)-4'-hydroxyacetanilide. The toxicity of 2,6-dimethylacetaminophen and 3,5-dimethylacetaminophen was examined histologically in mice and rats. 3,5-Dimethylacetaminophen was slightly more nephrotoxic but showed a similar hepatotoxicity to acetaminophen. 2,6-Dimethylacetaminophen, like N-methylacetaminophen, showed very little tissue damage.
- Fernando,Calder,Ham
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p. 1153 - 1158
(2007/10/02)
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