Organocatalytic enantioselective synthesis of β-amino sulfonic acid derivatives

An unprecedented enantioselective conjugate addition reaction of sodium bisulfite to various nitrostyrenes occurred upon the influence of a bifunctional amino-thiourea organocatalyst; a strategy that opens a straightforward route to unprotected chiral taurine derivatives thanks to the reduction of the obtained β-nitroethanesulfonic acids into the corresponding amino derivatives.

Ortho-Directed Palladium-Catalyzed Direct C–H Functionalization of 3-Picolinyl- and 3-(2-Cyanoethyl)pyrimidin-4(3H)-ones with Aryl Halides

The ortho-directed palladium-catalyzed direct C–H arylation of 3-picolinylpyrimidin-4-one was achieved by using various aryl halides. The method was extended to C–H arylation of pyrimidin-4-ones containing a methoxy group and an aryl group at the C5 site. The 2-cyanoethyl substituent was also evaluated as an ortho-directing group. The method gives access to novel N-substituted 2-aryl or 2,5-diaryl pyrimidin-4-ones. A standard three-step deprotection sequence for the picolinyl group was also studied.

Formation of Imidazolones by Ring Closure of α-Isocyanoamides: Exploring New Reactivities

Base-mediated ring closure of α,α-disubstituted α-isocyanoamides with further electrophilic trapping has previously been explored, but with limited applications. In this work, we wished to unravel the reactivities of these compounds and, in particular, to allow palladium-catalyzed coupling at the C2 position.

Pd(0)-Catalyzed Direct Inter- and Intramolecular C–H Functionalization of 4-Carboxyimidazoles

The palladium-catalyzed arylation and alkenylation of N-substituted methyl imidazole-4-carboxylates are described through inter- and intramolecular pathways. Both direct C2–H and C5–H arylation and alkenylation proceed under Pd(0)/Cu(I) cooperative catalysis and Pd(0) catalysis, respectively, in low-polarity 1,4-dioxane solvent. The methodology gives access to C2 (hetero)aryl or alkenyl imidazoles as well as innovative C2- and C5-arylated fused imidazoles tricycles with a five- to seven-membered middle ring.

Efficient Conversion of Epoxides into Carbonates with CO2 and a Single Organocatalyst: Laboratory and Kilogram-Scale Experiments

Cheap and readily available 2-aminopyridine and related compounds can be used as organocatalysts for the conversion of epoxides into cyclic carbonates. This reaction gives high conversions under solvent-free conditions and is amenable to a kilogram-scale conversion under mild conditions.

Isoform-selective HDAC1/6/8 inhibitors with an imidazo-ketopiperazine cap containing stereochemical diversity

A series of hydroxamic acids linked by different lengths to a chiral imidazo-ketopiperazine scaffold were synthesized. The compounds with linker lengths of 6 and 7 carbon atoms were the most potent in histone deacetylase (HDAC) inhibition, and were specific submicromolar inhibitors of the HDAC1, HDAC6 and HDAC8 isoforms. A docking model for the binding mode predicts binding of the hydroxamic acid to the active site zinc cation and additional interactions between the imidazo-ketopiperazine and the enzyme rim. The compounds were micromolar inhibitors of the MV4-11, THP-1 and U937 cancer cell lines. Increased levels of histone H3 and tubulin acetylation support a cellular mechanism of action through HDAC inhibition.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.

Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi₂⁺ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

["The Impact of Poverty on Elderly's Health in the District of Altona" Key Findings of The Second Altona Health Report]

OBJECTIVES

The aim of this study was to analyze whether health-related characteristics of elderly differ considering their income situation.

METHODS

N=322 elderly were included in a quantitative survey (e. g., SF36, GDS, Barthelindex, IADL). The evaluation was conducted in consideration of housing (independent, outpatient, nursing homes, district).

RESULTS

There were significantly higher values of diseases in the lower income than in higher income groups (F(316)=2,971; p=0,008; eta²=0,053). Furthermore the lower income groups were more often classified into long-term care level 2 (Chi²=25,36; p=0,009; C=0,283) associated with reduced abilities of daily living and lower scores on physical and mental wellbeing. Gender differences could not be found.

CONCLUSIONS

Low-income elderly have a poorer health status than high-income elderly. Endeavors should be undertaken to improve prevention strategies to retain independence and quality of life of low-income elderly.

Ligand-free Pd-catalyzed and copper-assisted C-H arylation of quinazolin-4-ones with aryl iodides under microwave heating

A microwave-assisted method for the palladium-catalyzed direct arylation of quinazolin-4-one has been developed under copper-assistance. This method is applicable to a wide range of aryl iodides and substituted (2H)-quinazolin-4-ones. This protocol provides a simple and efficient way to synthesize biologically relevant 2-arylquinazolin-4-one backbones.

Pd-Catalyzed direct C–H functionalization of imidazolones with aryl- and alkenyl halides

Direct C–H arylation and alkenylation of 4,4′-dialkylimidazolones with a broad range of halides under palladium and copper catalysis have been developed.

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds

The syntheses of new nitroimidazole compounds using silicon-[(18)F]fluorine chemistry for the potential detection of tumor hypoxia are described. [(18)F]silicon-based compounds were synthesized by coupling 2-nitroimidazole with silyldinaphtyl or silylphenyldi-tert-butyl groups and labeled by fluorolysis or isotopic exchange. Dinaphtyl compounds (6, 10) were labeled in 56-71% yield with a specific activity of 45 GBq/μmol, however these compounds ([(18)F]7 and [(18)F]11) were not stable in plasma. Phenyldi-tert-butyl compounds were labeled in 70% yield with a specific activity of 3 GBq/μmol by isotopic exchange, or in 81% yield by fluorolysis of siloxanes with a specific activity of 45 GBq/μmol. The labeled compound [(18)F]18 was stable in plasma and excreted by the liver and kidneys in vivo. In conclusion, the fluorosilylphenyldi-tert-butyl (SiFA) group is more stable in plasma than fluorosilyldiphenyl moiety. Thus, compound [(18)F]18 is suitable for further in vivo assessments.

Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source

We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au(60 +). The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

New family of peptidomimetics based on the imidazole motif

Starting from amino acid esters, new peptidomimetics based on the imidazole scaffold were prepared. An efficient and rapid sequence consisting of two subsequent one-pot procedures was developed and applied to various aminoacids. As they provide more substitution patterns, these heterocyclic mimics are promising tools for structural and biological studies.

Magnetization dynamics of Landau structures: tuning the response of mesoscopic magnetic objects using defects

Magnetic vortex cores are interacting with and can even be annihilated by artificial defects, such as holes. These defects have been fabricated by focused ion beam milling (FIB) into the magnetic domains, domain walls and the center of square-shaped vortices, known as Landau structures. We report the imaging of the magnetization dynamics of Landau structures containing holes by means of x-ray magnetic circular dichroism photo-emission electron microscopy (XMCD-PEEM). Due to the high lateral and temporal resolution of this method, the magnetic excitation spectrum, which is characteristic for the vortex-hole interaction, is investigated in detail. We find that the vortex core as well as domain walls can be trapped by small holes. With the help of micromagnetic simulations we show that the vortex gyrotropic motion frequency is enhanced, whereas the amplitude is significantly reduced in the case of non-centric holes in domain walls.

Premenopausal osteoporosis

While osteoporosis is a major public health concern, guidelines for diagnosis and treatment of low bone mass in the premenopausal population is lacking. Dual-energy x-ray absorptometry (DEXA) is a poor diagnostic tool to evaluate bone density in this population and the World Health Organization's definition of osteoporosis based on DEXA is not applicable to women before menopause. Bisphosphonates, while commonly used to treat postmenopausal osteoporosis, are not recommended in most premenopausal patients due to their long half-lives and side-effect profiles, therefore limiting the pharmacological interventions available. Secondary causes of low bone mass in premenopausal women include malnutrition, gastroenterological and hepatic disorders, endocrine disorders, and pharmaceutical use as well lifestyle characteristics. It is important to identify these risk factors in young women in order to encourage a lifestyle and a diet that minimize bone loss and to determine when pharmacologic intervention is necessary. In cases of secondary osteoporosis, treatment of the underlying disease process or cessation of the inciting medication, if possible, often results in normalized bone mass. Newer drugs with more benign side effect profiles and new methods of evaluating bone mass are being investigated and are likely to improve the evaluation and management of premenopausal women with low bone mass.

GaBi alloy liquid metal ion source for microelectronics research

A GaBi alloy liquid metal ion source has been studied. From an analysis of the source mass spectra as a function of emission current, a mechanism is suggested for the production of single- and double-charged ions. There is good agreement with the results of Swanson's investigations of a pure Bi source.

Anionic, in Situ Generation of Formaldehyde: A Very Useful and Versatile Tool in Synthesis

A very simple, safe and powerful method for the in situ generation of formaldehyde at low temperature in anhydrous conditions is described. This new tool avoids the use of gaseous formaldehyde and is suitable for basic carbon nucleophiles which cannot be generated in aqueous reaction media. Various substrates, including organolithium reagents and enolates, underwent smooth hydroxymethylation showing the versatility of this process. A Wittig reaction was also carried out in high yield. [reaction: see text]

One-Pot Synthesis of 2,3-Dihydro-pyrrolopyridinones Using in Situ Generated Formimines

A novel one-pot methodology is described for the synthesis of functionalized pyrrolopyridinones using in situ generated formimines and an ortho-lithiated pyridinecarboxamide species. Depending on the reaction conditions, this procedure allows versatile access to aminomethylated pyridinecarboxamides, 2,3-dihydro-pyrrolopyridinones, or 1,1-dialkylated 2,3-dihydro-pyrrolopyridinone derivatives. [reaction: see text]

Deprotonation of benzoxazole and oxazole using lithium magnesates

The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways: (1) the equilibration between the open and closed structures is faster than the trapping of the open isomers, and the closed isomers are more reactive than the open ones, or (2) the open isomers react with electrophiles in a intramolecular Passerini type reaction. The nonreactivity of the 2-(isocyano)enolate type structure toward anisaldehyde in the absence of lithium bromide makes the intramolecular Passerini type reaction more plausible.

Alloy liquid metal ion sources and their application in mass separated focused ion beams

For special purposes like writing ion implantation or ion mixing in the micrometer- or sub-micrometer range different ion species are needed. Therefore alloy liquid metal ion sources (LMISs) are used. The energy distribution of the ions from an alloy LMIS is one of the determining factors for the performance of a FIB column. Different source materials like Au(73)Ge(27), Au(82)Si(18), Au(77)Ge(14)Si(9), Co(36)Nd(64), Er(69)Ni(31), and Er(70)Fe(22)Ni(5)Cr(3) were investigated with respect to the energy spread of the different ion species as a function of emission current, ion mass and emitter temperature. The alloy LMISs discussed above have been used in the Rossendorf FIB system IMSA especially for writing implantation to fabricate sub-micrometer pattern without any lithographic steps. A Co-FIB was applied for the ion beam synthesis of CoSi(2) micro-structures. Additionally, the possibility of varying the current density with the FIB by changing the pixel dwell time was used for radiation damage investigations in Si and SiC at elevated implantation temperatures. Furthermore, a broad spectrum of ions was employed to study the sputtering process depending on temperature, angle of incidence and ion mass on a couple of target materials using the volume-loss method. Especially this technique was used for the fabrication of various kinds of micro-tools.