The Unexpected Formation of a 2,2′-Di( N -ethyl-acetamino)substituted Diphenyl Disulfane on Oxidation of 3-Ethyl-2-methylbenzothiazolium Tetrafluoroborate

Attempts at the oxidation of 3-ethyl-2-methylbenzothiazolium salt 2 with a variety of oxidizing reagents did not lead to the desired isochiral S -oxide 3 or achiral S , S -dioxide 4 , in some cases, however, unexpectedly to the ring-opened dimeric 2,2'-di( N -ethyl-acetamino)substituted diphenyl disulfane 5 , the molecular structure of which was confirmed by x-ray analysis. The synthesis of 2-methylbenzothiazole- S , S -dioxide 14 , reported by Zincke et al. in 1915, turned out to be not reproducible. \centerline{\epsfbox{:art:fig-01.jpg}}     

TETRATHIAFULVALENE S-OXIDE: A FATAL “DONOR IMPURITY” IN THE ORGANIC METAL TTF-TCNQ

Abstract

Tetrathiafulvalene S-oxide (TTF-ox) was first detected by mass spectrometry in samples of Tetrathiafulvalene (TTF) which had been exposed to oxygen. Pure TTF-ox was prepared by peracid oxidation of TTF and isolated as a relativly stable solid. Physical data will be presented.     

Scope and Applicability of an Expedient Synthesis Leading to Polysubstituted 3‐(Carboxyphenyl)pyrroles

A convenient three‐step route toward a functionalized pyrrole building block for novel anti‐inflammatory agents is reported. In contrast to previous strategies, the present approach focuses on inexpensive starting materials and application on a multigram scale. A high degree of functional diversity is demonstrated in various derivatives, and the scope and limitations of this route are discussed. Complementary to the described tetrasubstituted pyrroles, a novel ring‐closure protocol based on the Feist–Benary condensation affords trisubstituted analogues.     

Third-order Nonlinear Optical Properties of Octa-substituted Metal-free Phthalocyanine Thin Films

Third-order nonlinear optical susceptibility, χ⁽³⁾ of symmetrically octa-substituted metal-free phthalocyanine thin films measured by the third-harmonic generation technique are reported. The metal-free phthalocyanine has been found to show a χ⁽³⁾ (−3ω; ω,ω, ω) value as large as 7.73×10⁻¹² esu at 1.80 μm. The figure of merit, χ⁽³⁾/α, was estimated to be 4.17×10¹⁷ esu cm at 1.05 μm and 6.97×10¹⁶ esu cm at 1.65 μm. Both linear and third-order optical properties of liquid-crystalline metal-free phthalocyanines are discussed     

Kombinatorische Synthese

Industrial drug research is undergoing radical changes. Advances in molecular biology and gene technology have resulted in the development of test systems with which a very large number of substances can be screened for their biological activity. In order to keep pace with this high-throughput screening procedure, preparative chemists need to reconsider conventional synthetic strategies.     

Ring transformations of heterocyclic compounds. XIV . Ring transformations of pyrylium and thiopyrylium salts with anhydro-bases derived from 1H-benzimidazolium and benzothiazolium salts: An easy access to 2-(2,4,6-triarylphenyl) 1H-benzimidazolium and benzothiazolium derivatives

The preparation of former unknown 2-(2,4,6-triarylphenyl) substituted 1H-benzimidazolium perchlorates 7 and benzothiazolium perchlorates 8 from 2-methyl substituted derivatives 5/6 by a 2,6-[C₅+C] ring transformation of 2,4,6-triarylpyrylium and 2,4,6-triarylthiopyrylium salts 1/9 in the presence of an appropriate base ( 7 : sodium ethoxide, 8 : sodium acetate) is reported. Spectroscopic data of the transformation products and their mode of formation via anhydrobases of the salts 5/6 are discussed.     

Molecular imprinting of the endogenous neuropeptide Leu5-enkephalin and some derivatives thereof

We have undertaken the molecular imprinting of Leu⁵-enkephalin, and derivatives related to this endogenous neuropeptide, in highly cross-linked methacrylic acid/ethylene dimethacrylate copolymers. The underivatized enkephalin peptide yielded polymers with poor recognition abilities, since the imprinting of this compound had to be performed using dimethyl sulfoxide, which was found to interfere with the imprint inducement, as the solvent of polymerisation. In order to circumvent this problem, the amino- and carboxy-protected derivatives Boc-Leu⁵-enkephalin and Leu⁵-enkephalin anilide, which are soluble in apolar solvents, were investigated as alternative imprint molecules. Both compounds led to polymers which are highly specific for the imprint species. The anilide derivative was shown to be a good substitute for the free peptide since the resultant polymers showed efficient recognition of the parent enkephalin structure.