Rapid access to pyrido[1,2,5]triazepin-4-ones through intramolecular nucleophilic aromatic substitution

Several 3-substituted pyrido[1,2,5]triazepin-4-ones and their benzo counterparts have been prepared in three steps from commercial starting materials. The key step involves S_NAr-type intramolecular nucleophilic aromatic substitution of the appropriate hydrazone substrates.     

How glucosylation triggers physical–chemical properties of curcumin: an experimental and theoretical study

In the present study, we investigate the structures of glucosylated curcumin derivatives with DFT at B3LYP/6‐31G* level. A conformational analysis is performed in order to determine the conformational minimum (GS) and rotational transition state (TS) of curcumin derivatives and then their electronic features are evaluated. HOMO and LUMO frontier orbitals and maps of electron density potential (MEPs) are plotted and compared. In order to correlate their predicted spectroscopic properties with IR, UV–vis and NMR experimental data we extended the theoretical study on electronic properties to different solvents (H₂O, MeOH, ACN, DMSO). The main finding is that the curcuminic core maintains the same geometrical and electronic structures in all compounds miming the metal coordination capability showed by curcumin. Therefore, we may confirm that the presence of glucose does not affect the electronic properties of the derivatives. Copyright © 2010 John Wiley & Sons, Ltd.     

A Convenient and Rapid Preparation of Novel Quinoxaline Derivatives

A simple and rapid method for the preparation of a series of novel quinoxaline derivatives in the presence of Ag⁺ is reported.     

Survey of chemical residues and biological evaluation of photochemically pre-vulcanized surgical gloves

Abstract  

Latex allergies arise from the presence of latex proteins as well as noxious rubber additives (mainly accelerators and activators used in conventional sulfur-accelerated vulcanization processes) in medical devices (e.g., medical gloves, catheters) made from natural rubber latex. As a new approach the ultraviolet (UV) light-initiated pre-vulcanization of natural rubber latex makes efficient cross-linking feasible without using any toxic, mutagenic, or irritating chemicals. The cross-linking in the latex particles is accomplished via the thiol-ene addition reaction in the presence of a polyfunctional thiol and a photoinitiator. The new process is carried out in a falling film photoreactor on a pilot scale which provides a continuous irradiation of the latex emulsion. The UV technique is suitable for an easy up-scaling and represents the entrance into large-volume industrial production. The surgical gloves are then made by a conventional coagulant dipping process comprising good physical properties and high ageing stabilities. The aim of this study was to evaluate the biological properties and skin compatibility of UV-pre-cured gloves in skin sensitization, skin irritation studies, and cytotoxic tests. In addition the biologically available chemical residues in the gloves were characterized by UV–visible spectroscopy, elementary analyses, and high-performance liquid chromatography coupled with mass spectroscopy. The results of the studies revealed that UV-cross-linked surgical gloves exhibit good skin compatibility together with low cytotoxicity and residual chemical levels in the range of 60 and 120 μg/g_glove.     

Affinity chromatography on vancomycin coupled to reversed phase liquid chromatography/ electrospray-ion trap mass spectrometry for the screening of combinatorial libraries

Summary The combination affinity chromatography-mass spectrometry can be drastically improved by introducing a reversed phase column prior to the mass spectrometric detection. The interactions of the macrocyclic antibiotic vancomycin with oligopeptides were used to illustrate the performance of the technique. A library of 36 peptides was successfully screened and the active compounds identified by electrospray MS⁽ⁿ⁾. The strong affinity of compounds ending with (D)-alanine and with (D)-alanine or an aromatic (D)-amino acid in the penultimate position with vancomycin was confirmed.     

Trimethoxysilylpolymethacrylate as new material for stone conservation. Porosimetric and colorimetric investigations

Aimed to obtain new materials for the conservation of stone substrates, we report here on the synthesis of a polymer which has been obtained by inducing polymerization on a methacrylate monomer functionalized by alchoxysilane groups. Two lithotypes, the Comiso calcarenite and Mistretta quartzite, stones largely used in artworks of north-eastern Sicily, were treated with the above polymer and its conserving efficacy evaluated in terms of porosimetric features, hydric properties and appearance. The collected data were compared to those provided, under the same experimental conditions, by an ethylmethacrylate/methylmethacrylate copolymer and an alkylalchoxysilane, products widely employed in the protection of stones. Experiments aimed to test the durability of the above polymer against UV artificial ageing are also reported.     

Dialkylzinc-assisted alkynylation of nitrones

[reaction: see text]. Reaction of nitrones with terminal alkynes takes place readily in the presence of a substoichiometric amount of diethylzinc in toluene, affording N-propargyl-hydroxylamines in excellent yields and purity.