Enantiopure bicyclic piperidinones: stereocontrolled conjugate additions leading to substituted piperidinones

The conjugate additions of Reformatsky reagents, organocuprate reagents, and hydroxylamines to a [4.3.0]-bicyclic enelactam derived from 6-oxopipecolic acid have been investigated, and found to be efficient, proceeding with excellent exo-stereocontrol, with the exception of N-benzyl-O-benzylhydroxylamine, which gives predominantly the product of endo-addition. These adducts can be readily converted to substituted piperidinones.     

Cellulose, St?ke, Rohzucker und Melassen

Ohne Zusammenfassung     

Solubilization of itraconazole as a function of cyclodextrin structural space

Cyclodextrins are functional pharmaceutical excipients, which can dynamically include poorly water-soluble drugs and drug candidates resulting in improved solubility, stability and oral bioavailability. A number of formulations containing “natural” and chemically modified cyclodextrins have reached the market and are enjoying widespread attention and use. One such example is itraconazole, a broad-spectrum antifungal agent which is available in an aqueous hydroxypropyl-β-cyclodextrin (HPβCD) vehicle for both oral and parenteral use (Sporanox Oral Solution and Sporanox Intravenous Injection^®). While the interaction of itraconazole and HPβCD is well described, its ability to form complexes with other cyclodextrins is less understood. This creates an intriguing opportunity of screening the structural space of available cyclodextrin derivates by assessing their complexation with a single chemical probe, in this case itraconazole. To this end, a number of cyclodextrin derivatives were assess with regard to their ability to improve the water solubility of the test substrate. In some instances, more detail assessments including the effect of pH and the physical form of the drug probe were also completed. The various cyclodextrins solubilized itraconazole to varying extents (micrograms to milligrams) and by varying inclusion mechanisms and stoichiometries.     

Fingerprinting food: current technologies for the detection of food adulteration and contamination

Major food adulteration and contamination events seem to occur with some regularity, such as the widely publicised adulteration of milk products with melamine and the recent microbial contamination of vegetables across Europe for example. With globalisation and rapid distribution systems, these can have international impacts with far-reaching and sometimes lethal consequences. These events, though potentially global in the modern era, are in fact far from contemporary, and deliberate adulteration of food products is probably as old as the food processing and production systems themselves. This review first introduces some background into these practices, both historically and contemporary, before introducing a range of the technologies currently available for the detection of food adulteration and contamination. These methods include the vibrational spectroscopies: near-infrared, mid-infrared, Raman; NMR spectroscopy, as well as a range of mass spectrometry (MS) techniques, amongst others. This subject area is particularly relevant at this time, as it not only concerns the continuous engagement with food adulterers, but also more recent issues such as food security, bioterrorism and climate change. It is hoped that this introductory overview acts as a springboard for researchers in science, technology, engineering, and industry, in this era of systems-level thinking and interdisciplinary approaches to new and contemporary problems.     

RADIATIVE HEAT TRANSFER AUGMENTATION IN GAS-FIRED RADIANT TUBE BURNERS BY POROUS INSERTS: EFFECT OF INSERT GEOMETRY

This article presents the results of an experimental investigation of heat transfer augmentation by porous media in a natural gas-fired radiant tube burner. The results show that significant heat transfer augmentation is possible with the use of porous ceramic inserts in both premixed and nonpremixed gas-fired radiant tube burners. Furthermore, this work has shown that geometry variations in the porous insert configuration can appreciably alter both heat transfer rates and mixing and chemical reaction rates in these systems. In the case of nonpremixed flames, the effect of variation of insert geometry is more than simple heat transfer augmentation via gas enthalpy conversion to thermal radiation by the porous medium. There is also a significant alteration of the reactive gas mixing (and therefore chemical reaction and heat release) rates along the length of the tube. The basic mechanisms that control the mixing rate and heat release distribution in these systems are still unknown. Nevertheless, it appears reasonable to expect that optimal operating conditions (uniform, maximum heat flux and temperature; and even minimal NO_x emissions) can be achieved, at least in the diffusion burner case, solely through porous insert geometric configuration variations.