Angélique Ferry

Heterogeneously Catalyzed Direct CH Thiolation of Heteroarenes

The first general methodology for the direct thiolation of electron-rich heteroarenes was developed by employing Pd/Al2 O3 , a recoverable and commercially available heterogeneous catalyst, and CuCl2 . This method represents an operationally simple approach for the synthesis of these valuable compounds. Preliminary mechanistic studies indicate a heterogeneous catalytic system, in which both metals play a complementary role in the formation of the thiolated products.

New Route to Stabilize Ruthenium Nanoparticles with Non‐Isolable Chiral N‐Heterocyclic Carbenes

Ru nanoparticles (RuNPs) stabilized by non-isolable chiral N-heterocyclic carbenes (NHCs), namely SIDPhNp ((4S,5S)-1,3-di(naphthalen-1-yl)-4,5-diphenylimidazolidine) and SIPhOH ((S)-3-((1S,2R)-2-hydroxy-1,2-diphenylethyl)-1-((R)-2-hydroxy-1,2-diphenylethyl)-4,5-dihydro-3H-imidazoline), have been synthesized through a new procedure that does not require isolation of the free carbenes. The obtained RuNPs have been characterized by state-of-the-art techniques and their surface chemistry has been investigated by FTIR and solid-state MAS NMR upon the coordination of CO, which indicated the presence of free and reactive Ru sites. Their catalytic activity has been tested in various hydrogenation reactions involving competition between different sites, whereby interesting differences in selectivity were observed, but no enantioselectivity.

Synthesis, characterization, and coupling reactions of six-membered cyclic P-chiral ammonium phosphonite-boranes; Reactive H-phosphinate equivalents for the stereoselective synthesis of glycomimetics

Stereoselective syntheses of P-chiral ammonium phosphonite-borane complexes in the gluco- and manno-like series have been developed from P(V) phostone derivatives. The coupling reactions of these phostone donors with alcohols have been investigated with particular emphasis on the influence of protecting groups and conditions on stereoselectivity. The phosphonite-borane complexes may be applied directly in the coupling reactions and the products oxidized in situ to give phostone-mimetics of disaccharides. On the basis of these studies, successful protocols were established for the synthesis of β-gluco and α- and β-manno-configured phostones of primary alcohols. Deprotection of the dimeric compounds leads to novel families of α- or β-(1→6)-linked glycomimetics.

N-O bond as a glycosidic-bond surrogate: synthetic studies toward polyhydroxylated N-alkoxypiperidines.

A series of novel polyhydroxylated N-alkoxypiperidines has been synthesized by ring-closing double reductive amination (DRA) of highly functionalized 1,5-dialdehydes with various hydroxylamines. The required saccharide-based dialdehydes were prepared efficiently from sodium cyclopentadienylide in seven steps. A two-step protocol has been developed for the DRA; it led, after deprotection, to isofagomine, 3-deoxyisofagomine, and numerous other N-alkoxy analogues. The barrier to inversion in these polyhydroxylated N-alkoxypiperidine derivatives was found by variable-temperature NMR methods to be approximately 15 kcal mol(-1). With the exception of N-hydroxyisofagomine itself, none of the compounds prepared showed significant inhibitory activity against sweet almond β-glucosidase.

Alternative Synthesis of P-Chiral Phosphonite-Borane Complexes: Application to the Synthesis of Phostone–Phostone Dimers

An improved strategy for the synthesis of P-chiral gluco- and manno-phosphonite-borane complexes is described on the basis of the addition of diethyl phosphonite-borane to a glucal-derived aldehyde, followed by a cyclization coupled with an ethyl/methyl exchange. This direct P(III) strategy facilitates the obtention of various P-chiral phosphonite-boranes, of which further coupling reactions are described leading to the selective synthesis of two phostone dimers.

Synthesis and Evaluation of Di- and Trimeric Hydroxylamine-Based β-(1→3)-Glucan Mimetics

Di- and trimeric hydroxylamine-based mimetics of β-(1→3)-glucans have been accessed by an asymmetric synthesis route featuring an iterative double ring-closing reductive amination reaction. These oligomeric hydroxylamines are demonstrated to inhibit the staining of human neutrophils and of mouse macrophages by fluorescent anti-CR3 and anti-dectin-1 antibodies, respectively, and to stimulate phagocytosis, all in a linkage-dependent manner suggestive of binding to the lectin domains of complement receptor 3 (CR3) and dectin-1. The ability of these relatively short mimetics to bind to CR3 and dectin-1, as compared to the greater degree of polymerization required in β-(1→3)-glucans, is discussed in terms of the increased hydrophobicity of the α-face on replacement of the glycosidic bond by the hydroxylamine linkage.

Influence of the Headgroup of Azolium-Based Lipids on Their Biophysical Properties and Cytotoxicity

A series of (un-)charged NHC derivatives bearing two pentadecyl chains in the backbone was studied in detail to find cooperative effects between the membrane and the NHC derivative. The tendency to show lipid-like behavior is dependent on the properties of the NHC derivative headgroup, which can be modified on demand. The surface activity was investigated by film balance measurements, epifluorescence microscopy, and differential scanning calorimetry. Additionally the cytotoxicity was evaluated against different cell lines such as eukaryotic tumor cell lines. These novel lipid-like NHC derivatives offer a broad spectrum for biological applications.

Synthesis of C-pyrimidyl nucleosides starting from alkynyl ribofuranosides

The synthesis of four C-pyrimidyl nucleosides is described by condensation of small nitrogen molecules (amidines and ureas) onto alkynyl riboside derivatives. These last compounds were obtained by indium mediated stereoselective alkynylation of suitably protected ribose derivatives and the condensation reaction conditions were studied in order to favor the N-attack of the nitrogen molecules leading to the pyrimidine ring formation.

When Phosphosugars Meet Gold: Synthesis and Catalytic Activities of Phostones and Polyhydroxylated Phosphonite Au(I) Complexes

The synthesis and characterization of P-chiral phosphonite-, phosphonate- and thiophosphonate-Au(I) complexes are reported. These novel ligands for Au(I) are based on glycomimetic phosphorus scaffolds, obtained from the chiral pool. The catalytic activities of these complexes are shown in the cyclization of allenols and the hydroamination of 2-(2-propynyl)aniline combined with an organocatalyzed reduction to the corresponding 2-phenyl tetrahydroquinoline. All described gold complexes present excellent catalytic activities.