Institut de Chimie Moléculaire et des Matériaux d'Orsay

Catalyse homogène — Chimie de coordination — Chimie Organométallique — Chimie du Palladium — Chimie de l’Or — Chimie du Gallium — Propriétés électroniques des ligands — Chimie du carbone divalent — Chimie des métaux nobles — Chimie des métaux du groupe principal — Chimie du Fer.

Iron catalysis

The borrowing hydrogen strategy has been applied to the ethylation of imines, using an air-stable iron complex as precatalyst. This approach has opened new perspectives in this area, as it allowed the synthesis of unsymmetric tertiary amines from readily available substrates and ethanol as C2-building block. A variety of imines bearing electron-rich aromatic or alkyl groups at the nitrogen atom could be efficiently reductively alkylated, without requiring the use of molecular hydrogen.

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We have developed new families of cationic Ga(I), Ga(III), In(I) and In(III) catalysts able to imitate the behavior of noble transition metal complexes in π-acid catalysis or transfer hydrogenation. These species exhibit either NHC or fluorobenzene ligands. They behave as soft Lewis acids able to trigger the formation of highly delocalized non-classical carbocations from alkynes and alkenes. They are especially useful in skeletal reorganization reactions leading to polycyclic compounds after C-C or C-H bond formation.

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In order to improve the overall efficiency of gold-catalyzed transformations, we have discovered that Cu(I) and Cu(II) salts could activate LAuCl precatalysts, while lowering their decay into inactive nanoparticles. This decomposition phenomenon is typically observed with Ag(I) activators, which are commonly used to generate the active cationic gold complex. On the other hand, the Au/Cu catalytic system proved versatile and allowed to carry out a variety of reactions with very low loadings of the gold precatalyst and without requiring tedious ligand design. Indeed, simple phosphines could be used successfully on gram-scale reactions.

 

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We have exploited the exceptional σ-Lewis acidity of Ca(II) complex, sometimes exacerbated by the use of hexafluoroisopropanol as solvent (HFIP), to activate electron-poor C=C bonds in hydroamination reactions, or to activate Csp3-O bonds for the synthesis of carbocycles or oxygen- or nitrogen-containing heterocycles. In particular, the low-tech air-stable calcium pre-catalyst Ca(NTf2)showed an exceptional versatility in reactions leading to furans, pyrroles or pyrrolidines.

 

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Calcium(II)-Catalyzed Intra- and Intermolecular Hydroamidation of Unactivated Alkenes in Hexafluoroisopropanol Alcohol. C. Qi, F. Hasenmaile, V. Gandon, D. Lebœuf, ACS Catalysis, 2018, 8, 1734-1739