Synthesis of β-Enaminoesters and Lactams by Michael Addition of N-Benzylaniline to New Allenic Esters and Lactams

The synthesis of original allenic lactams 2 and allenic esters 5 is presented and their Michael condensation with N-benzylaniline described.     

A ring-closing metathesis approach to secosteroidal macrocycles

An efficient synthesis of secosteroidal macrocycles has been achieved via an oxidative ring-expansion/ring-opening sequence and a ring-closing metathesis reaction as the key steps.     

Improved Copper(I)–NHC Catalytic Efficiency on Huisgen Reaction by Addition of Aromatic Nitrogen Donors

A simple addition with a large impact : Addition of aromatic amines such as phenanthroline and 4‐DMAP (4‐dimethylaminopyridine) increases copper(I)‐catalyzed azide alkyne cycloaddition (CuAAC) catalytic activity of [CuCl(SIMes)] at a large range of temperatures in such a way that efficient catalysis can safely take place in hydro‐alcoholic solvents (see scheme).

     

Optical and Calorimetrical Studies of Liquid Crystalline Materials Doped with Nanoparticles

Summary: Electro-optical properties of Polymer Dispersed Liquid Crystal (PDLC) films doped with different nanoparticles (NPs), as well as optical and morphological properties of liquid crystal/NP mixtures have been investigated. PDLC films were prepared by UV irradiation of thiol-ene monomers and liquid crystal E7 in the presence of a small amount (0.5 and 1 wt.%) of nanoparticles. The presence of NP strongly influence the properties of liquid crystal/NP mixtures. In particular, adding nanoparticles results in a decrease of the glass and nematic-isotropic transition temperatures of the LC, suggesting that strong interactions occur between LC and nanoparticles.     

Considération sur l'ordre des acidités successives du diacide 7-para carboxy anilino 4-nitrobenzofurazane

On the dissociation constants of successive acidities of the diacid 7-para carboxy anilino-4-nitrobenzofurazane. The first dissociation constant of the 7-para carboxy anilino-4-nitrobenzofurazane noted 4H,COOH, in dimethylsulfoxyde was estimated using an NMR method. Diacid 4H,COOH was prepared by simple reaction of aromatic nucleophilic substitution (S_NAr) and monopotassium salt and was precipitated by chloroform addition to a solution of 4H,COOH in Me₂SO, after neutralisation of an acid function by one equivalent of solid potassium bicarbonate. Initially, a titration NMR ¹H of two acidities of 4H,COOH was carried out in Me₂SO-d₆ by the strong base potassium tert-butoxide. After, we showed that ionization NH/N⁻ is carried out completely before that of function COOH. We could estimate the first dissociation constant (7.5) of 4H,COOH in dimethylsulfoxyde by using the 9-cyano fluorene as a reference compound.     

Luminescent properties of Yb-doped monoclinic yttrium polyphosphates

Yb³⁺-doped monoclinic yttrium polyphosphate Y(PO₃)₃ powder compounds were synthesized and were characterized by X-ray diffraction, IR absorption spectroscopy and Raman scattering spectroscopy.An attempt to use Yb³⁺ ion as structural probe is carried out to investigate the site occupation. Yb³⁺ emission and fluorescence decay studies were carried out both at low and room temperatures. The interpretation of electronic energy level positions has been done by using the comparison of emission spectra with those of vibronic sideband energy positions from Raman scattering spectroscopy.The spectroscopic results are discussed and correlated with the data of the already known monoclinic structure of Y(PO₃)₃ where four slightly different octahedral sites are available for the trivalent rare earth ion.     

Out-patient Queues at the Ibn-Rochd Health Centre

An arbitrary policy of fixing the number of outpatient appointments specifying the dates (and not the exact times) of appointments created long queues and large waiting times in some departments of the Ibn-Rochd health centre, but considerable idle time for the consulting doctors in others. After narrating in detail these circumstances and examining a number of possible options, this paper describes the scientific approaches made to determine the number of appointments, the corresponding parameters of the queue and the system and the service per cent occupation.Finite source size, a random number of initial patients, group arrivals, non-exponential service time distribution, late start-up of the servicing unit and many other factors combined to render available theoretical results difficult to apply and results obtained by applying approximately equivalent theoretical models unreliable as compared with those observed in real life. It is shown that simulation could be more profitably applied in such situations.     

Pyrrolizidine alkaloids from Solenanthus lanatus DC. with acetylcholinesterase inhibitory activity

The whole plant ethanolic extract of Solenanthus lanatus was used for the isolation of acetylcholinesterase inhibitors. A new pyrrolizidine alkaloid, 7-O-angeloylechinatine N-oxide, 1, was isolated together with three known compounds of the same class (3′-O-acetylheliosupine N-oxide, 2, heliosupine N-oxide, 3, and heliosupine, 4), by bioassay-guided approach. Their structures were elucidated by spectroscopic methods. All the isolated compounds showed inhibition activity against the AChE, with IC₅₀ 0.53–0.60 mM.