The adsorption and decomposition of carbon monoxide on Ni(100) and the oxidation of the surface carbide by oxygen

The interaction of carbon monoxide with Ni(100) has been studied by ellipsometry and Auger electron spectroscopy. Bombardment by electrons of a relatively high energy (2500 eV) leads to the disproportionation of the adsorbed CO (2 COad → Cad + CO2g ). The rate of oxidation of this surface carbide is , where hc is the carbon 272 eV Auger peak height, n=0.5 and the apparent activation energy Eact =13.3 kcal/mole. This relation is valid at 200–400°C and at oxygen pressures of 5 × 10−9−8 × 10−7 Torr

The conformation of tetrafluorinated methyl galactoside anomers: crystallographic and NMR studies

The first single-crystal X-ray diffraction study of tetrafluorinated monosaccharide derivatives is presented.Both a- and b-methyl 2,3-dideoxy-2,2,3,3-tetrafluoro-D-galactopyranoside anomers adopt the4C1 conformation. The values for the C1–O1 and C1–O5 bond lengths and the O5–C1–O1–CH3 dihedralangles are in line with what can be expected from the anomeric and exo-anomeric effects. The chair conformationsare slightly distorted, presumably due to repulsion between 1,3-diaxial C–O and C–F bonds.The asymmetric unit of both compounds contains up to three independent molecules, which differ inthe conformation of the hydroxymethyl group (including in one case a ‘forbidden’ gg rotamer). Themolecular packing of the b-anomer shows a clear segregation between fluorinated and hydrophilicdomains, while for the a-anomer the regions of fluorine segregation are broken by interleafing of OMegroups. There is one close OH? ? ?F contact, which is likely to arise from the crystal packing. NMR studiesshow that the two anomers also adopt a 4C1 conformation in solution (D2O, CDCl3)

Efficient access to fluorinated homoallylic alcohols through an indium promoted fluoroallylation reaction

International audienc

Toward the Synthesis of Fluorinated Analogues of HCV NS3/4A Serine Protease Inhibitors Using Methyl α‑Amino-β-fluoro-β-vinylcyclopropanecarboxylate as Key Intermediate

Synthesis of fluorocyclopropyl building blocks, which constitute the core of various therapeutic agents against the hepatitis C virus, is described. The relevant methyl α-amino-β-fluoro-β-vinylcyclopropane­carboxylate has been used as a key intermediate for the total synthesis of a fluorinated analogue of Simeprevir (TMC 435), a HCV NS3/4A protease inhibitor

High-order harmonic wave fronts generated with controlled astigmatic infrared laser

International audienceWe report an experimental study on the control of the high-order harmonic wave front through the adjustment of the wave front of the fundamental infrared laser. We have applied different levels of astigmatism to the IR beam via the use of a deformable mirror placed before the lens, and demonstrated that there exists a correlation between the IR and the high harmonic wave fronts