The synthesis of (+)- and (−)-1-benzoyl-1,2,2a,3,4,5-hexahydrobenz[cd]indol-4-amine, and preparation of LY228729.

Racemic epoxide5 was reacted with S-Phenylethylamine to afford diastereomers6 and7, from which amino alcohol6 could be isolated directly. Aziridine formation and tandem-hydrogenolysis provided optically pure primary amine2 (31% from racemic4), which was further elaborated to LY228729 (15), an interesting 5HT_1a receptor agonist.     

Depsipeptide dendrimers

The convergent synthesis of a new class of chiral dendrimers is described. Owing to their structural resemblance to depsipeptides they are called depsipeptide dendrimers. The ex-chiral pool synthesis starts from (R,R)-, (S,S)-, and meso-tartaric acid as branching units and dipeptides or tripeptides consisting of glycine, (L)-alanine, and (L)-leucine as chiral-spacer building blocks. The key intermediates for the convergent assembly of such depsipeptide dendrimers are the peptide-tartaric acid conjugates 13a,b, 19a,b, 25, and 27, which contain either an unprotected C terminus of the peptide chain (13 a,b, 25) or two unprotected hydroxy groups within the tartaric acid termini. Dendra up to the third-generation, by using different combinations of stereoisomeric building blocks, were synthesized and completely characterized. Since this construction principle of chiral depsipeptide dendrimers allows for a wide variation of the length, the primary structure of the peptide spacer, and the configuration of both the amino acid and the tartaric acid moieties, access to new combinatorial libraries is conceptually provided.     

Recent comparability of oceanographic nutrients data: results of a 2003 intercomparison exercise using reference materials.

An intercomparison exercise was conducted using the recently developed Reference Material for Nutrients in Seawater (RMNS). Discrepancies of reported values among laboratories were greater than the homogeneity of RMNS samples and the reported analytical precision of nutrients. The variability of in-house standards of the participating laboratories might be the most likely source of interlaboratory discrepancies. Therefore, the use of common reference materials, i.e. certified RM, is essential to establish and improve the comparability of nutrient data of the world's oceans.     

Chemistry of pyrimidine. Proton magnetic resonance study of covalent hydration across the 3,4-carbon-nitrogen bond of 5-substituted pyrimidines

Pyrimidines containing 5-substituents which are weakly or strongly electron withdrawing undergo covalent hydration across the 3,4-carbon-nitrogen bond in aqueous acid. The degree of hydration was measured by proton magnetic resonance spectroscopy and was found to be dependent on the strength of the acid media and the electron withdrawing power of the 5-substituent.     

Use of column switching for the determination of niacinamide in compound feed

A high-performance liquid chromatographic method is described for the determination of niacinamide in compound feed. The niacinamide is extracted with 0.2 M hydrochloric acid in order to suppress the hydrolysis of the niacinamide to nicotinic acid. The chromatography is carried out with the aid of column switching. An RP-18 column is used for the preseparation, and the analytical separation takes place in a cation-exchange column. With the proposed method, the limit of determination is about 2 ppm of niacinamide.     

Site distribution in resin beads as determined by confocal Raman spectroscopy

Scanning confocal Raman spectroscopy was used to study the distribution of reactive sites within a resin bead used for solid-phase synthesis. The distribution of NH2 groups in aminomethylated polystyrene resin (APS) was determined by doping with varying amounts of 4-cyanobenzoic acid. The extent of loading was determined by both elemental analysis and ninhydrin assays. The spatial distribution of the coupled 4-cyanobenzamide within the bead was determined to an in-plane resolution of 1 microm and depth resolution of about 4 microm, using the strong Raman CN stretching vibrational transition at 2230 cm(-1). Dry and swollen beads were studied and the distribution was found to be essentially uniform throughout the bead in all cases.     

Finding the needles in the haystack: efficient intelligence processing

As a result of communication technologies, the main intelligence challenge has shifted from collecting data to efficiently processing it so that relevant, and only relevant, information is passed on to intelligence analysts. We consider intelligence data intercepted on a social communication network. The social network includes both adversaries (eg terrorists) and benign participants. We propose a methodology for efficiently searching for relevant messages among the intercepted communications. Besides addressing a real and urgent problem that has attracted little attention in the open literature thus far, the main contributions of this paper are two-fold. First, we develop a novel knowledge accumulation model for intelligence processors, which addresses both the nodes of the social network (the participants) and its edges (the communications). Second, we propose efficient prioritization algorithms that utilize the processor’s accumulated knowledge. Our approach is based on methods from graphical models, social networks, random fields, Bayesian learning, and exploration/exploitation algorithms.     

The quantum hypernetted chain model of warm dense matter

Modeling warm dense matter, where a combination of partial ionization, partial electron degeneracy, and strong ion–ion and ion–electron coupling occur, is a frontier of equation of state research. We present the quantum hypernetted chain model which can be applied to studies of liquid metals, warm dense matter, and plasmas. This is an all-electron model that considers a mixture of a classical fluid of ions (with bound electrons) and a quantum electron fluid. The model describes self-consistently the structure of the ion fluid as well as the bound states of the ions and the non-linear response of the electron fluid. We present our initial results and compare them with experimental and ab initio results for liquid metals and low-temperature plasmas.     

Asymmetric catalysts for stereocontrolled olefin metathesis reactions

Since the discovery of metathesis as an instrument to reorganize olefinic double bonds, substantial progress has been attained, establishing this method as a versatile and efficient tool for C-C-bond formation. In the last decade fundamental achievements were accomplished in the field of chiral Ru- and Mo-based olefin metathesis, providing an asymmetric access to structures, which are difficult to obtain by alternative routes. The reader is taken behind the scenes of catalyst development, important areas of application are described up to the current state of research; this tutorial review deals with the question, how metathesis is connected to enantioselective synthesis.