Unprecedented Biomimetic Homodimerization of Oroidin and Clathrodin Marine Metabolites in the Presence of HMPA or Phosphonate Salt Tweezers

The first biomimetic homodimerization of oroidin and clathrodin was effected in the presence HMPA and diphosphonate salts, strong guanidinium and amide chelating agents. The intermolecular associations probably interfere with the entropically and kinetically favored intramolecular cyclizations. Use of oroidin·¹/₂HCl salt or clathrodin·¹/₂HCl was indicative in the presence of the ambident nucleophilic and electrophilic tautomers of the 2-aminoimidazolic oroidin and clathrodin precursors. Surprisingly, the homodimerization of oroidin led to the nagelamide D skeleton, while the homodimerization of clathrodin gave the benzene para-symmetrical structure <b>19</b>. The common process was rationalized from tautomeric precursors <b>I</b> and <b>III</b>

Concise synthesis of Didebromohamacanthin A and Demethylaplysinopsine: Addition of Ethylenediamine and Guanidine Derivatives to the Pyrrole-Amino Acid Diketopiperazines in Oxidative Conditions

Oxidative nucleophilic addition of ethylenediamine and guanidine derivatives to pyrrole-amino acid diketopiperazines was shown to provide substituted 5,6-dihydro-2­(1<i>H</i>)-piperazinones, quinoxalinones, and 2-aminoimidazolones. On the basis of this methodology, a concise approach to natural products didebromohamacanthin A and demethylaplysinopsine has been demonstrated

Uma experiência de tradução do conto “Marcha Fúnebre” de Machado de Assis para o japonês

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Reporter Ligand NMR Screening Method for 2‑Oxoglutarate Oxygenase Inhibitors

The human 2-oxoglutarate (2OG) dependent oxygenases belong to a family of structurally related enzymes that play important roles in many biological processes. We report that competition-based NMR methods, using 2OG as a reporter ligand, can be used for quantitative and site-specific screening of ligand binding to 2OG oxygenases. The method was demonstrated using hypoxia inducible factor hydroxylases and histone demethylases, and <i>K</i>_D values were determined for inhibitors that compete with 2OG at the metal center. This technique is also useful as a screening or validation tool for inhibitor discovery, as exemplified by work with protein-directed dynamic combinatorial chemistry

Plant Growth Regulator Daminozide Is a Selective Inhibitor of Human KDM2/7 Histone Demethylases

The JmjC oxygenases catalyze the <i>N</i>-demethylation of <i>N</i>^ε-methyl lysine residues in histones and are current therapeutic targets. A set of human 2-oxoglutarate analogues were screened using a unified assay platform for JmjC demethylases and related oxygenases. Results led to the finding that daminozide (<i>N-</i>(dimethylamino)­succinamic acid, 160 Da), a plant growth regulator, selectively inhibits the KDM2/7 JmjC subfamily. Kinetic and crystallographic studies reveal that daminozide chelates the active site metal via its hydrazide carbonyl and dimethylamino groups