Synthesis of ansamycins: An approach to the naphthoquinone portion of the rifamycins and streptovaricins

Naphthoquinone $\text{1}$, a fully functionalized model for intermediates in ansamycin synthesis, was prepared by the intramolecular Claisen condensation of benzofuran $\text{9}$ followed by oxidation of the novel tricyclic compound $\text{10}$.     

Group selective reduction of acetals related to the ansa chain of the streptovaricins: Conformational and stereochemical analysis

The group selective reductive cleavage of benzylidene acetals derived from diols containing chains equipped with a central chirotopic, nonstereogenic carbon atom is reported. The stereochemistry that is obtained at the central carbon is suitable for application to the synthesis of members of the streptovaricin class of antibiotics.     

List of publications of Prof. Dr. H. J. Seifert

List of publications of Prof. Dr. H. J. Seifert     

S.C.F.M.O. study of Hafner's hydrocarbons

SCF MO calculations have been made for Hafner's hydrocarbons using neglect of differential overlap after the manner ofPople andPariser andParr. ^* transitions have been calculated by a limited configuration interaction method. The results show that agreement between predicted spectra and observed spectra is quite good for the heptalene derivative and reasonably good for the pentalene derivative. It is suggested that both molecules are aromatic in contradiction to predictions by Craig's rule.

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Zusammenfassung SCF MO-Rechnungen mit zero differential overlap nach der Methode vonPople, Pariser undParr wurden fürHafner's Kohlenwasserstoff angestellt. Mittels begrenzter Konfigurationswechselwirkung (wurden)die ^*-Übergänge berechnet, wobei die Ergebnisse im Fall des Heptalen-Derivates verhältnismäßig gut, in dem des Pentalen-Derivates jedoch nur ungefähr mit dem Experiment übereinstimmen. Darüber hinaus sprechen die Resultate im Gegensatz zur Craig'schen Regel dafür, daß beide Moleküle aromatischen Charakter haben.

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Résumé Nous avons effectué des calculs SCF MO pour les hydrocarbures deHafner, en négligeant le recouvrement différentiel d'aprèsPople etPariser etParr. Quelques transitions ^* ont été calculées par interaction de configurations limitée. L'accord avec l'expérience est assez bon pour le dérivé de l'heptalène, et raisonable pour le dérivé du pentalène. Les deux molécules semblent être aromatiques, contrairement à la règle de Craig.

     

60th Birthday of Prof. Dr. Dr. h.c. Heino Finkelmann

This section contains news of the macromolecular community all over the world. Articles about, for example, people, projects, and market trends are welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de. The editorial office decides which articles will be published.     

Aromatic annelation. I. Synthesis of pyridines.

The preparation of substituted pyridines from cycloalkanones by elaboration of an aromatic ring is described.     

An E.P.R. study of peptides after U.V. irradiation

Abstract— Various peptides of Gly, Ala, Phe, Tyr, and Trp have been irradiated with U.V. light in the solid state or in frozen aqueous solution. The radicals produced were studied by E.P.R. spectroscopy at low temperature and at room temperature. Radicals seem to occur preferentially on Gly or Ala when in the C-terminal position and there is evidence for a photosensitization of these amino acids by aromatic amino acids.     

Aromatic Annelation. II. Synthesis of phenols.

The preparation of substituted phenols from cycloalkanones by elaboration of an aromatic ring is described.     

Magnetic Recording of N.Q.R. spectra

This paper gives complete details of a unique system for Magnetically Recording the Analogue Spectral Signals from an N.Q.R. Spectrometer of the S.R.O./Marginal Oscillator type.This is a very low cost system, but producing a very high order of play-back resolution from recordings, using a normal domestic Cassette or Tape, Reel to Reel Recorder. Spectra can also be transmisted via telephone lines, fibre optic links or radio frequencies.This system has been used now for several years, and due to the design being based mainly om passive components, the order of reliability is extremely high, without any faults being encountered to dete!.