Abstract Upon treatment with TBAF, CF3-substituted N-allenamides were transformed into γ-sultams. Cyclic sulfonamides bearing an ene-gem-difluorinated tether could be obtained by addition of acetic acid to the ammonium salt whereas TBAF alone provided the correspondingtrifluorinated ethyl sultams. A combined experimental and computationnal mechanistic study suggested that this transformation...[En savoir plus]
Abstract Cu chelation in biological systems is of interest as a tool to study the metabolism of this essential metal or for applications in the case of diseases with a systemic or local Cu overload, such as Wilson's or Alzheimer's disease. The choice of the chelating agent must meet several criteria. Among others, affinities and kinetics of metal binding and related metal selectivity are...[En savoir plus]
Abstract Copper (Cu) is essential for most organisms, but it can be poisonous in excess, through mechanisms such as protein aggregation, trans-metallation and oxidative stress. Latter could implicate the formation of potentially harmful Reactive Oxygen Species (ROS: O2•–, H2O2 and HO•) via the redox cycling between Cu(II)/Cu(I) states in the presence of dioxygen and physiological reducing agents...[En savoir plus]
Abstract In the field of noncovalent interactions, chalcogen bonding (ChB) involving the tellurium atom is currently attracting much attention in supramolecular chemistry and in catalysis. However, as a prerequisite for its application, the ChB should be studied in solution to assess its formation and, if possible, to evaluate its strength. In this context, new tellurium derivatives bearing CH2F...[En savoir plus]
Abstract Telluronium salts bearing electron-withdrawing groups were prepared, and their ability to drive chalcogen bonds with ketones and imines was demonstrated in the solid state and in solution. These strong σ-hole bond donors were able to efficiently catalyze the Povarov reaction through chalcogen bond activation of imines and subsequent reaction with alkenes. The title reaction was found to...[En savoir plus]
Abstract Eukaryotic life appears to have flourished surprisingly late in the history of our planet. This view is based on the low diversity of diagnostic eukaryotic fossils in marine sediments of mid-Proterozoic age (around 1,600 to 800 million years ago) and an absence of steranes, the molecular fossils of eukaryotic membrane sterols1,2. This scarcity of eukaryotic remains is difficult to...[En savoir plus]
Abstract A multi-responsive receptor consisting of two (acridinium-Zn(II) porphyrin) conjugates has been designed. The binding constant between this receptor and a ditopic guest has been modulated (i) upon addition of nucleophiles converting acridinium moieties into the non-aromatic acridane derivatives and (ii) upon oxidation of the porphyrin units. A total of eight states has been probed for...[En savoir plus]