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Salimabromide is an antibiotic polyketide that was previously isolated from the obligate marine myxobacterium Enhygromyxa salina, and its densely functionalized and conformationally rigid tetracyclic framework is unprecedented in nature. Herein we report the first chemical synthesis of the target structure by employing a series of well-orchestrated, robust transformations, highlighted by an acid-promoted, powerful Wagner-Meerwein rearrangement/Friedel-Crafts cyclization sequence to forge the two adjacent quaternary carbon centers embedded in the tetrahydronaphthalene. A high-yielding ketiminium mediated [2+2]-cycloaddition was also utilized for the simultaneous construction of the remaining three stereocenters.

We describe the evolution of a synthetic strategy for the construction of the marine polyketide salimabromide. Combining a bicyclo[3.1.0]hexan-2-one ring-expansion to build up a functionalized naphthalene and an unprecedented rearrangement/cyclization cascade, enabled synthesis of a dearomatized tricyclic subunit of the target compound. Alternatively, an intramolecular ketiminium [2+2]-cycloaddition and subsequent Baeyer-Villiger ring-expansion gave access to the sterically encumbered architecture of salimabromide. Sequential oxidation of the carbon framework finally enabled the total synthesis of this unusual natural product.

Fusarium head blight (FHB) in triticale (× Triticosecale Wittmack) results in yield losses and mycotoxin contamination, for example, by deoxynivalenol (DON). This study aimed to analyse the correlation between FHB severity and DON content in a DH population of 146 entries across environments. Additionally, Fusarium damaged kernel (FDK) rating, heading stage and plant height were recorded. Highly significant (P

Described is the development of a highly efficient 2π disrotatory ring-opening aromatization sequence using bicyclo[3.1.0]hexan-2-ones. This unprecedented transformation efficiently proceeds under thermal conditions and allows facile construction of uniquely substituted and polyfunctionalized benzoates. In the presence of either amines or alcohols formation of substituted anilines or ethers, respectively, is achieved. Additionally, the utility of this method was demonstrated in a short synthesis of sekikaic acid methyl ester.

This review highlights the chemistry of trihaloethene building blocks with a special focus on commercially available 1,1,2-trichloroethene. The topics surveyed herein include the use of trihaloethenes as C2-building blocks for transition metal-catalyzed coupling reactions, addition, elimination and cycloaddition reactions as well as natural product syntheses.

We report the synthesis of orthogonally functionalized naphthalenes from simple, commercially available indanones in four steps. The developed method proceeds through a two-step process that features a thermally induced fragmentation of a cyclopropane indanone with simultaneous 1,2-chloride shift. Migration of the chloride substituent occurs in a regioselective manner to preferentially afford the para-chloronaphthol substitution pattern. The obtained naphthols are versatile building blocks that can be selectively modified and used for the efficient construction of biologically active molecules. This has enabled the total synthesis of the potent anticancer natural product chartarin through a highly convergent retrosynthetic bond disconnection.

This review highlights the chemistry of trihaloethene building blocks with a special focus on commercially available 1,1,2-trichloroethene. The topics surveyed herein include the use of trihaloethenes as C2-building blocks for transition metal-catalyzed coupling reactions, addition, elimination and cycloaddition reactions as well as natural product syntheses.

Described is the development of a highly efficient 2π disrotatory ring-opening aromatization sequence using bicyclo[3.1.0]hexan-2-ones. This unprecedented transformation efficiently proceeds under thermal conditions and allows facile construction of uniquely substituted and polyfunctionalized benzoates. In the presence of either amines or alcohols formation of substituted anilines or ethers, respectively, is achieved. Additionally, the utility of this method was demonstrated in a short synthesis of sekikaic acid methyl ester.

The results of investigations on corona charged thin mesogenic films consisting of solid mixtures of achiral liquid crystalline side-chain polymers and their monomers are presented. A pyroelectric modulation and a low frequency piezoelectric technique were used to confirm the polar properties of these compounds. The pyroelectric coefficient γ and the apparent longitudinal piezoelectric coefficient d33 were measured in the glassy state to be 3.2 nC/cm2K and 9 pC/N. The pyroelectric currents versus modulation frequency for various polar materials were studied for comparison.

We report on the application of in situ electroabsorption measurements for the evaluation of local electric field distributions in double layer polymer films. The temporal dependence of the measured signal indicates that besides the relation of ohmic resistivities of the different polymer layers, the influence of the electric properties of polymer/electrode and polymer/polymer interfaces must also be considered for the DC field, which is present in the electrooptic active layer.

The use of a direct reading photoionization detector (PID) to determine short-term solvent exposures is described in the present paper. To assess the relevance of such a total exposure evaluation it was necessary to compare it with the real concentration of pollutants. This comparison was made by measuring in parallel with the PID determination the concentration of each pollutant using a standard technique, i.e. sampling on charcoal tubes and subsequent analysis by gas chromatography. Laboratory tests showed that the linearity of the answer of the PID is good for many compounds and for a mixture of these compounds. Similar tests were carried out for painters in workplaces with the same good correlations (determination coefficient r 2 close to 1) between the PID response and the real concentration of the pollutants measured on the sampling tubes. The use of PID also allowed determination of the exposure profile of the workers and comparison of the short-term exposure to the corresponding limit values. Many cases of the short-term limit values being exceeded were revealed by use of the PID, although very few cases of the long-term limit values have been found by the usual sampling (charcoal tube) and analytical (gas chromatography) methods.

The mobility of dye molecules in a polymer matrix was investigated by use of electroabsorption and dielectric relaxation spectroscopy. The electroabsorption spectroscopic method is selective to the relaxation processes of the chromophores embedded in a matrix. The technique can be used to determine the fast relaxation processes at higher temperatures which are not observable in time domain as well as for observation of slow processes below the glass transition point.

The extraction of phytic acid was performed mostly by means of hydrochloric acid containing sodium sulphate. Trichloroacetic acid (TCA) was also recommended as an extractant. The concentration of TCA was widely varied to reach complete extraction. As the minimum solubility of iron phytate was found in the range of pH 2.5−8.0 the question arises whether a quantitative precipitation of the complex takes place at lower pH. The paper is concerned with the conditions of maximum precipitation of iron phytate from a TCA-containing extract

We report on a method to investigate the inhomogeneous distribution of an electric dc field in multilayer polymer stacks. In situ electroabsorption (EA) measurements are applied in order to estimate the local electric fields in double layer polymer films. The observed time dependent behaviour is compared with a model equivalent circuit. The results indicate that besides the relation of ohmic resistivities and capacities of the different polymer layers in the investigated systems also the influence of the electric properties of polymer/electrode and polymer/polymer interfaces must be considered.

Electroabsorption spectroscopy (Stark spectroscopy) was used to characterize the poling process of three guest–host systems containing stilbene, azobenzene, and biphenyl dyes in a polycarbonate matrix. The poling was carried out at room temperature by application of a dc field under simultaneous irradiation of the sample with nonpolarized light. Investigating different types of chromophore permitted evaluation of the influence of a local heating process on the whole poling mechanism. The intensity dependence of the induced polar order of the azobenzene dye was correlated with the rates of optical and thermally induced transitions between cis and trans isomers.

The orientational behaviour of a variety of phosphonic acid diesters dissolved in different liquid crystalline phases of pentoxy-benzylidene-hexylaniline was studied. For the complete determination of the orientational ordering of the phosphonate segment, partially deuteratcd esters were synthesized and a combination of 31P, 2H and 1H NMR was used. For solutions of hexane phosphonic diethyl ester dissolved in the nematic and SA phases, the order parameter, S33 increases from 0.22 to 0.42 with a biaxiality of 0.1. The CH2 P(O)O2, segment is in the trans-conformation and the Sv axis makes an angle of 22° with the P=0 bond. In the SB phases the value of S31 of the phosphonate segment decreases dramatically to a value of 0.1 in contrast to that of the molecules of the matrix. The reason is that the solute molecules are excluded from the more ordered aromatic region and are forced into the less-ordered hydrocarbon chain region of the matrix. In the SG phase, a phase separation occurs. In diethyl ester...

Es wurden Pyridin-Analoga vom Fentanyl-Typ synthetisiert und im hot-plate-Test auf analgetische und am Kaninchen auf atemdepressive Wirkung gepruft. Synthesis and Pharmacological Screening of Fentanyl Analogues Pyridine analogues of Fentanyl were synthesized and tested for analgesic activity according to the hot-plate procedure with mice and for respiratory depressive action in the rabbit.

The total number of patients we treated for cancer of the skin was sixty. In order to characterise this group of patients it will suffice to say that only twelve of the whole group had not been subjected to an operation or to treatment with ray energy previous to the application of radon. All the others had been subjected to repeated operations, to treatment with roentgen rays and radium, as well as to operative treatment combined with the application of ray energy. This precedent treatment either gave no results whatever, or after a certain improvement in the patient's condition, or even the patient's recovery, his condition again became worse or a recidivation of the disease occurred. Those patients had been affected with the disease for many years, and some of them had been subjected to treatment with ray energy for years. It is evident that those were not cases of epithelioma remaining for a long period in statu quo, which are covered with a crust, and have a tendency to heal due to the application of...