Systematic synthesis and characterization of a series of different bromoalkylglycosides by Fischer glycosylation.

In order to investigate the possibilities of Fischer glycosylation towards the synthesis of bromoalkylglycosides we performed a variety of different reactions resulting in a small library of 16 different glycosides. Using standardized reaction conditions we could gain a broad range of results from small to higher yields. Finally we randomly selected three reactions and performed them with higher amounts of bromoalcohol resulting in significantly better yields, showing the optimization potential of these basic research work.

Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties.

Six polymerizable N,N'-diacylamides containing spatially arranged N-acryl, N-allyl and/or N-alkyl groups were prepared via two-step syntheses and characterized by 1H/13C NMR-spectra, refractive index (RI) and viscosity measurements. Photo DSC measurements on activated samples provided reactivity parameters ∆Hp, Rp,max and tmax, while FTIR spectra before and after curing elucidated the underlying polymerization mechanism. Mechanical testing of the obtained polymers exhibited gradual differences in network densities, depending on the intramolecular arrangement and number of functional groups. Overall, a general building principle for highly reactive, liquid diacrylamides via synergistic combination of optimally arranged functional groups could be identified. The highest possible level of intramolecular synergism was found for low viscous N,N'-diacryloyl-N,N'-diallyl-1,4-but-2-enediamine.

Studies toward the synthesis of linear triazole linked pseudo oligosaccharides and the use of ferrocene as analytical probe.

Three different building blocks have been synthesised and used for the synthesis of linear triazole linked pseudo oligosaccharides with copper(I)-catalysed cycloaddition (CuAAC). Ethynylferrocene has been used as analytical probe to improve the UV/Vis properties and HPLC methods have been used and optimised for the analysis of the pseudo oligosaccharides. The smallest ones have been isolated and characterised by analytical HPLC, NMR, ESI-MS and elemental analysis.

Preferential Extracellular Generation of the Active Parkinsonian Toxin MPP+ by Transporter-Independent Export of the Intermediate MPDP+.

AIMS: 1-Methyl-4-phenyl-tetrahydropyridine (MPTP) is among the most widely used neurotoxins for inducing experimental parkinsonism. MPTP causes parkinsonian symptoms in mice, primates, and humans by killing a subpopulation of dopaminergic neurons. Extrapolations of data obtained using MPTP-based parkinsonism models to human disease are common; however, the precise mechanism by which MPTP is converted into its active neurotoxic metabolite, 1-methyl-4-phenyl-pyridinium (MPP(+)), has not been fully elucidated. In this study, we aimed to address two unanswered questions related to MPTP toxicology: (1) Why are MPTP-converting astrocytes largely spared from toxicity? (2) How does MPP(+) reach the extracellular space? RESULTS: In MPTP-treated astrocytes, we discovered that the membrane-impermeable MPP(+), which is generally assumed to be formed inside astrocytes, is almost exclusively detected outside of these cells. Instead of a transporter-mediated export, we found that the intermediate, 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP(+)), and/or its uncharged conjugate base passively diffused across cell membranes and that MPP(+) was formed predominately by the extracellular oxidation of MPDP(+) into MPP(+). This nonenzymatic extracellular conversion of MPDP(+) was promoted by O2, a more alkaline pH, and dopamine autoxidation products. INNOVATION AND CONCLUSION: Our data indicate that MPTP metabolism is compartmentalized between intracellular and extracellular environments, explain the absence of toxicity in MPTP-converting astrocytes, and provide a rationale for the preferential formation of MPP(+) in the extracellular space. The mechanism of transporter-independent extracellular MPP(+) formation described here indicates that extracellular genesis of MPP(+) from MPDP is a necessary prerequisite for the selective uptake of this toxin by catecholaminergic neurons.

Carbohydrate-based Cu(I) stabilizing ligands and their use in the synthesis of carbohydrate-ferrocene conjugates.

A series of carbohydrate-ferrocene conjugates have been synthesized by copper(I)-catalyzed cycloaddition of carbohydrate-azides and ethynylferrocene (CuAAC). Newly carbohydrate-based tris-triazoles have been used as Cu(I) stabilizing ligands and showed at least comparable, in some cases even better results compared to the use of tris-(benzyltriazolylmethyl)amine (TBTA).

UV-induced immobilization of tethered zirconocenes on H-terminated silicon surfaces.

A tethered ethylenebis(indenyl) zirconocene was covalently immobilized on H-terminated Si(111) surfaces using UV-mediated alkene hydrosilylation, thus making possible the development of structured catalytic surfaces with highly controlled properties.