Diastereoselective Hartwig-Buchwald reaction of chiral amines with rac-[2.2]paracyclophane derivatives.

A Hartwig-Buchwald addition of a variety of chiral amines to rac-4-bromo-[2.2]paracyclophane and rac-trifluoromethanesulfonic acid (4-[2.2]paracyclophane) ester was performed with high diastereoselectivities.

Enolate addition to a 2-alkylidene[1,3]dithiane-derived bissulfoxide. A new a(2)-acceptor.

Reaction of enolates derived from esters and ketones to an easily prepared alkylidene[1,3]dithiane-1,3-dioxide afforded the respective adducts with good yields and selectivities generally exceeding 85:15. The base used for enolate addition played no significant role for the reaction outcome, and addition of a silyl enole ether gave similar results. The thus formed oxygenated S,S-acetals were transformed into the corresponding 1,4-dicarbonyls by a reduction/oxidation sequence with 84% yield.

Modelling of short QT syndrome in a heterogeneous model of the human ventricular wall.

Aims: A percentage of sudden cardiac death events occur in individuals with structurally normal hearts due to an abnormality in the ion channel activity. While the majority of these hereditary syndromes are well-established, little is known about the significance of the short QT syndrome.

Methods: This study is based on discovered insights into the molecular basis of the originally described form of this disease.

Organic azides: an exploding diversity of a unique class of compounds.

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science.

Unusual syntheses, structures, and electronic properties of compounds containing ternary, T3-type supertetrahedral M/Sn/S anions [M5Sn(mu3-S)4(SnS4)4](10- (M = Zn, Co).

A recently discovered series of quaternary compounds of the general type [K(m)(ROH)(n)()][M(x)Sn(y)()Se(z)] (R = H, Me), containing ternary anions with [SnSe(4)](4-)-coordinated transition metal centers (M = Co, Mn, Zn, Cd, Hg) has now been extended by the synthesis and characterization of the two ortho-thiostannate-coordinated species, [Na(10)(H(2)O)(32)][M(5)Sn(mu(3)-S)(4)(SnS(4))(4)].2H(2)O (M = Zn (1), Co (2)). The central structural motifs of compounds 1 and 2 are highly charged [M(5)Sn(mu(3)-S)(4)(SnS(4))(4)](10-) anions, being the first T3-type supertetrahedral ternary anions reported to date.

Synthesis, control of substitution pattern and phase transitions of 2,3-di-O-methylcellulose.

An improved heterogeneous procedure has been found for the regioselective introduction of trityl and 4-methoxytrityl groups at the primary positions of cellulose. The 6-O-tritylcelluloses produced were completely methylated by MeI-NaOH in Me2SO solution. The trityl groups were then completely removed to afford 2,3-di-O-methylcellulose without significant degradation of the polymer.

Analytic calculation of first-order molecular properties at the explicitly correlated second-order Moller-Plesset level: basis-set limits for the molecular quadrupole moments of BH and HF.

The analytic calculation of first-order properties has been implemented in the DALTON program at the level of explicitly correlated second-order Moller-Plesset perturbation theory (MP2-R12). The implementation has been accomplished for MP2-R12 theory based on standard approximations A, A', and B, using an auxiliary basis for the resolution-of-the-identity approximation, with and without a frozen core. MP2-R12 first-order molecular properties have been calculated analytically for a few small test molecules.

Efficient solid phase synthesis of benzo[1,2,3]thiadiazoles and related structures.

The first solid-phase synthesis of benzo[1,2,3]thiadiazoles was achieved by starting from resin bound ortho bromo or iodo triazenes and using a functionalization on cleavage.

Structurally diverse second-generation [2.2]paracyclophane ketimines with planar and central chirality: syntheses, structural determination, and evaluation for asymmetric catalysis.

A set of 20 novel [2.2]paracyclophane ketimines with planar and central chirality has been synthesized from enantiomerically pure and racemic 5-acyl-4-hydroxy[2.2]paracyclophane and alpha-branched chiral amines.

Coupled-cluster theory with simplified linear-r(12) corrections: the CCSD(R12) model.

A simplified singles-and-doubles linear-r(12) corrected coupled-cluster model, denoted CCSD(R12), is proposed and compared with the complete singles-and-doubles linear-r(12) coupled-cluster method CCSD-R12. An orthonormal auxiliary basis set is used for the resolution-of-the-identity approximation to calculate three-electron integrals needed in the linear-r(12) Ansatz. Basis-set convergence is investigated for a selected set of atoms and small molecules.

Determination of porosity and flow distribution in packed beds by magnetic resonance imaging.

Magnetic resonance methods have been used to investigate the porosity and flow distributions in packed beds. The motivation of our study is to understand the behaviour of multiphase flow in fixed bed reactors, especially in trickle bed reactors. The results of this study should be included in a model for predicting the influence of hydrodynamics on hydrodesulfurization process in bench-scale reactors.

NMR investigation of gaseous SF6 confinement into EPDM rubber.

The confinement process of gaseous sulphurhexafluoride (SF6) in ethylene-propylene-diene (EPDM) rubber was investigated by spectroscopic and spatially resolved NMR techniques. A strong elongation of T1 relaxation time of SF6 and a decrease of the diffusion coefficient were found. A possible explanation may be the strong restriction of molecular mobility due to interactions between SF6 and active centers of the EPDM.

Variation of the carrier-envelope phase of few-cycle laser pulses owing to the Gouy phase: a solid-state-based measurement.

The carrier-envelope phase of a laser pulse has recently become an important quantity in extreme nonlinear optics. Because of the topological Gouy phase, it changes while the pulse propagates through the focus of a lens. This variation is measured by a simple solid-state-based approach.

Total synthesis of alternariol.

Total synthesis of alternariol, a toxic secondary metabolite of various Alternaria fungi, was achieved in seven steps starting with orcinol and 3,5-dimethoxybromobenzene. The longest linear sequence consists of six steps. Key reaction is a palladium-catalyzed Suzuki-type coupling of an orcinol-derived boronic acid with a brominated resorcylic aldehyde.

3'-immobilized probes with 2'-caps: synthesis of oligonucleotides with 2'-N-methyl-2'-(anthraquinone carboxamido)uridine residues.

[reaction: see text] A synthesis for oligodeoxynucleotides with a 3'-terminal 2'-N-methyl-2'-acylamido-2'-deoxyuridine residue was developed. Unlike their unmethylated counterparts, these oligodeoxynucleotides can be stably immobilized on aldehyde-displaying glass surfaces to provide DNA microarrays. An anthraquinone carboxamido group as a 2'-substituent doubled the capture efficiency of an immobilized tetradecamer.

Pontin and Reptin regulate cell proliferation in early Xenopus embryos in collaboration with c-Myc and Miz-1.

Pontin (Tip49) and Reptin (Tip48) are highly conserved components of multimeric protein complexes important for chromatin remodelling and transcription. They interact with many different proteins including TATA box binding protein (TBP), beta-catenin and c-Myc and thus, potentially modulate different pathways. As antagonistic regulators of Wnt-signalling, they control wing development in Drosophila and heart growth in zebrafish.

Design and performance of a planar-array MIT system with normal sensor alignment.

In this study the performance of a planar array for magnetic induction tomography (MIT) was investigated and the results of measurements to determine the precision and sensitivity of the sensor were undertaken. A planar-array MIT system utilizing flux-linkage minimization for the primary field has been constructed and evaluated. The system comprises 4 printed excitation coils of 4 turns which were shielded, 8 surface-mount inductors of inductance 10 microH as sensor, mounted such that in principle no primary-field flux threads them, and a calibration coil to produce a strong primary field.

Stabilized nanoparticles of phytosterol by rapid expansion from supercritical solution into aqueous solution.

The basic objective of this work was to form stable suspensions of submicron particles of phytosterol, a water-insoluble drug, by rapid expansion of supercritical solution into aqueous solution (RESSAS). A supercritical phytosterol/CO2 mixture was expanded into an aqueous surfactant solution. In these experiments 4 different surfactants were used to impede growth and agglomeration of the submicron particles resulting from collisions in the free jet.

Zebralike patterned organic conductor with periodic modulation of mobility and Peierls transition.

We manipulated the defect concentration in a (fluoranthene)2PF6 crystal by proton irradiation through a periodic grid, resulting in a striped defect pattern. Spatially resolved pulsed X-band ESR analysis was used to quantify the resulting local defect concentrations, spin diffusion coefficients, and electron spin concentrations. The temperature dependence of the data proves that spin diffusion coefficient and Peierls transition can be tailored in a controlled way via the defect concentrations.

Microstructure analysis of a carbon-carbon composite using argon ion etching.

The microstructure of carbon-carbon composites obtained by chemical vapor infiltration of a carbon fiber felt was comparatively studied by reflection light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and laser scanning confocal microscopy (LSCM). Ar+ ion etching was used to reveal and distinguish structural units of the pyrolytic carbon matrix. Mechanically polished samples, polished and subsequently ion etched samples, and fractured samples were compared.