Addition of a Chiral Copper Reagent Derived from Propargylic Oxazolidininone to Aldehydes

International audienceThe copper reagent arising from an optically pure propargylic oxazolidinone was found to react regio- and diastereoselectively with aldehydes, leading, in a one-pot procedure, to the anti homopropargylic amino alcohols derivatives in good yields

Tandem superelectrophilic activation for the regioselective chlorofluorination of recalcitrant allylic amines

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Tuning the nuclearity of [Mo2O2S2]2+ -based assemblies by playing with the degree of flexibility of bis-thiosemicarbazone ligands

International audience[MoV2O2S2]2+-based thiosemicarbazone complexes appear as very promising molecules for biological applications due to the intrinsic properties of their components. This paper deals with the synthesis and characterization of six coordination complexes obtained by the reaction of [MoV2O2S2]2+ clusters with bis-thiosemicarbazone ligands that contain flexible or rigid spacers between the two thiosemicarbazone units. Interestingly, structural characterization by single-crystal X-ray diffraction, MALDI-TOF MS technique and NMR spectroscopy revealed that the nuclearity of the complex is controlled by the nature of the spacer between the thiosemicarbazone units. Binuclear complexes, namely [MoV2O2S2(L1–3)], are isolated with flexible spacers while tetranuclear complexes [(MoV2O2S2)2(L4–6)2] are formed when the bis-thiosemicarbazone ligands are built on rigid spacers

Host–guest adaptability within oxothiomolybdenum wheels: structures, studies in solution and DFT calculations

The formation of host–guest cyclic architectures, built up through the self-condensation process of [Mo2O2S2]2+ oxothiocations around linear dicarboxylate ions such as adipate (Adip2−), suberate (Sub2−) and azelaate (Azel2−) anions is reported. The complexes [Mo12Adip]2−, [Mo12Sub]2− and [Mo14Azel]2− have been characterized in the solid state by X-ray diffraction and in solution by 1H NMR in different solvents (D2O, DMF, DMSO and CD3CN). The host–guest dynamics appear to be dependent on the nature of the system and are mainly governed by mutual adaptability between the host and the guest. 1H NMR DOSY experiments show systematic differences, either positive or negative between the experimental and calculated molecular weights which appear to be correlated with the charge of the anion. The relative stabilities of the twelve-membered rings containing the Adip2−, Pim2− (pimelate) or Sub2− anions were determined experimentally and decrease according to the order [Mo12Adip]2− > [Mo12Pim]2− > [Mo12Sub]2−. The host–guest adaptability depends on the length of the carbon chain and gives rise to selective encapsulation processes. Finally, theoretical DFT investigations in the gas phase yielded conformations whose symmetry and geometrical parameters proved consistent with X-ray structures and 1H NMR spectra recorded in DMSO or DMF. Energy calculation highlights the high flexibility of the ring showing that only 3.1 kJ mol−1 accompanies the conformational change from circular to elliptical. The host–guest bond energy (ΔE) calculated for the Mo12-based clusters is consistent with the experimental stability scale, major variations being due to some constraints undergone by the central alkyl chain