Stereoselective synthesis of erythro-β-hydroxy carboxylic acids via iron acyl complexes

β-Hydroxy acyl ligands bound to (η⁵-C₅H₅)Fe(CO)(PPh₃) are stereoselectively alkylated on the α-carbon to give after decomplexation erythro-β-hydroxy carboxylic acids.     

Identification of amber and imitations by near infrared reflection spectroscopy

Imitations of amber have been prepared since a long time, but the number of imitations is increasing since modern polymers are available. At present, many imitations are based on a few synthetic polymers and even experts have some problems in distinguishing between real and falsed amber without destruction of the material. IR-Spectroscopy or pyrolysis combined with gas chromatography/mass spectrometry are very efficient methods in identifying amber and imitations but these methods need a sample preparation. By means of near infrared reflection spectroscopy it is possible to identify amber and imitations without any sample preparation in a short time. Optimization of the method and the application are discussed.     

Relative reactivities of some dienes and acetylenes in copolymerization with sulfur dioxide

The reactivities of isoprene, piperylene,2,3-dimethylbutadiene, hex-1-yne, and phenylacetylene, at ?20°C, relative to that of cyclohexene, have been determined for the radical-initiated copolymerization with sulfur dioxide to form 1:1 polysulfones. The unsaturated hydrocarbons were copolymerized with sulfur dioxide in pairs and the composition of the terpolymers determined from the 100 MHz NMR spectra. The dienes react 11–15 times as fast as hex-1-ene, while hex-1-yne reacts 16 times more slowly. Phenylacetylene reacts 21 times as fast as hex-1-yne. The relative reactivities are interpreted mainly in terms of the effect of electron delocalization on the stability of the product radical.     

Synthesen und chemisches Reaktionsverhalten neuer überbrückter Chinonderivate. Kupplungsreaktionen von Diazoniumsalzen mit 2-Methoxy-1,6-methano [10]annulen

Syntheses and Chemical Properties of New Bridged Quinone Derivatives. Coupling Reactions of Aryldiazonium Salts with 2-Methoxy-1,6-methano[10]annulene Coupling of 2-methoxy-1,6-methano[10]annulene (3) with the aryldiazonium salts 4a-4i yields the quinone hydrazones 5a-5i. The spectroscopic properties of these products are described. The reaction of 3 with 4-nitrophenyldiazonium tetrafluoroborate buffered with sodium acetate in dry methanol yielded after chromatographic separation the azo derivative 7 on the one hand and a mixture of the valence tautomers 8a and 8b on the other.     

First successful reaction of a silyl anion with hafnium tetrachloride

Hafnium tetrachloride reacts with the tris(trimethylsilyl)silyl potassium tmen adduct (1) to form a [tris(trimethylsilyl)silyl]trichlorohafnium tmen complex (2); reaction of 2 with 2,6-dimethylphenylisonitrile leads to insertion into the silicon hafnium bond (4).     

Biochemical and biomedical applications of capillary column GLC using SIM

This report focuses on recent applications of capillary column GLC to the analysis of drugs and metabolites, other xenobiotics, natural products, and environmental contaminants in samples of biological origin. The increasing use of selected ion monitoring, combined with stable isotope methods as a means of GLC detection and quantification, is emphasized. Specific topics covered include the use of capillary column GLC for 1) determining the pharmacokinetics of timolol (BLOCADREN) in human volunteers by simultaneous oral and intravenous administration of this beta-blocker and its 13C3-labeled analog; 2) measuring residue levels of the forced molting agent, xylonidine, in yolk and albumen of chicken eggs; 3) monitoring animal plasma and tissues for the depletion of 5-hydroxy-1,3-dioxane and 4-hydroxymethyl-1,3-dioxolane (isomeric components of glycerol formal, an animal drug formulation component); 4) detecting 13C, 15N-methyltryptamine (a biosynthesis product from 13C, 15N-tryptamine) in human urine; and 5) measuring estradiol levels in biological samples.     

Aromatic Radical Anions with Parallel or Crossed Triple Bonds

Proton hyperfine data are reported for the radical anions of 1,8-di (propyn-1-yl)-naphthalene (I), 7,8,12,13-tetradehydro-10,11-dihydro-9H-cyclodeca[d,e]naphthalene (II) and 2,2′-di(propyn-1-yl)-biphenyl (III), as well as of 5,6,11,12-tetradehydro-7,8,9,10-tetrahydro-dibenzo[a,c]cyclodecene (IV) and its 8,8,9,9-tetradeuterio-derivative (IV-d₄). The triple bonds in I and II can be regarded as roughly parallel, while those in IV (and IV-d₄) may be considered as crossed. The π-spin distributions in I? to IV? are discussed in terms of simple MO models which suggest a weekly bonding interaction between the acetylenic fragments in IV?, in contrast to III? where such an effect appears to be negligible. The importance of an analogous interaction in I? and II? is difficult to deduce, since its inclusion into a MO model does not substantially affect the π-spin distribution in these radical anions.     

Zerlegungen der Grenzgruppe des einfach-isotropen Raumes Jn

According to Strubecker an affine metric n-space (J_n,g) over a field F of char. 2 (n2) is called simply-isotropic if Radg is one-dimensional; let Fu be the totally isotropic direction w.r. to g. The group B_g of motions of (J_n,g) contains an invariant (2n–1)-dimensional subgroup G, called thelimit group (Grenzgruppe) which maps planes parallel to Fu into parallel ones. In case n=3, n=5, F= Strubecker [12], [13], [14] gave several factorizations G=G_L oG_R of G into a commutative product of subgroups acting 1-transitively (=regularly) on J_n.This note deals with all factorizations of this kind; it followes that n must be odd. A factorization is invariant under B_g iff n=3. Finally it is shown for each factorization of G how the space J_n can be made into a two sided incidence group and into a kinematic space in the sense of Karzel [5], and how the two structures are related to each other.

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Herrn Professor Dr. Karl Strubecker zum 75. Geburtstag gewidmet     

“… to make Chemistry more Applicable and Generally Beneficial”—The Transition in Scientific Perspective in Eighteenth Century Chemistry

In 1751, the Swedish chemist Johan Gottschalk Wallerius first differentiated between “pure” and “applied” chemistry, a distinction which was quickly adopted by the other branches of science. Behind this was a new scientific concept of chemistry which emphasized the importance of applying chemistry's accumulated knowledge and its capabilities of providing for the general economic benefit. It also provided chemistry with a new position within the hierarchy of the sciences as well as with a new function in society. The reasons behind and causes of the change in scientific perspective associated with this concept point to the social and institutional conditions under which this field has developed into an independent academic discipline.     

The synthesis of the potent anti-herpes virus agent, E-5(2-bromovinyl)-2′-deoxyuridine and related compounds

The synthesis of $\text{E}$-5(2-bromovinyl)-2′-deoxyuridine in good yield from deoxyuridine $\text{via}$ an intermediate organopalladium derivative is described. The corresponding chloro and iodo compounds have also been made as have the corresponding bromo and iodo 2′-deoxycytidines.