Magnetic circular dichroism studies 23. 1. Magnetic circular dichroism spectra of indole alkaloids

The magnetic circular dichroism spectra of a number of indole alkaloids show two B-terms of opposite sign in the 250–330 nm wavelength region associated with the ¹L_b and ¹L_a electronic transitions, the long wavelength, ¹L^b, band being of positive sign, whereas both bands strongly overlap in absorption. Various substituents in different positions of the indole ring cause a red shift of both bands and a broadening of the long wavelength B-term. The sign pattern, howver, remains unchanged in all examples thus far investigated. Dihydroindole and oxindole, on the other hand, exhibit MCD. bands with the opposite sign sequence as compared to the indole chromophore. This observation allows identification of the indole chromophore in alkaloids from the sign pattern of the MCD. bands.     

Elektronenstossinduzierte Fragmentierung von Acetylenverbindungen. IX—Struktur der Stabilen [C9H11]+-Ionen aus Isomeren C9H11-Chloriden

The structure of stable [C₉H₁₁]⁺ ions from different model compounds with the molecular formula C₉H₁₁Cl has been estimated by energy measurements. It has further been shown that acetylenic compounds cyclise to form aromatic ions in the range of the appearance potentials.     

Methylthiomethylierung von Anilinen und Phenolen, 3. Mitt.: Darstellung von N-Aryl-S,S-dialkylsulfimiden

Zusammenfassung Aus Anilinen, die im aromatischen Ring mit CH₃, CH₃SCH₂, CH₃O, Cl, Br oder NO₂ substituiert sind, und Sulfoxiden wird in Anwesenheit von P₄O₁₀ und Triäthylamin eine Reihe von N-Aryl-S,S-dialkylsulfimiden erhalten. Diese Reihe umfaßt Verbindungen mit CH₃-, C₂H₅- und –(CH₂)₄-Gruppen am Schwefelatom. Das Sulfimid aus Mesidin lagert sich—formal analog zu einerSommelet—Hauser-Umlagerung—zum 2,4,6-Trimethyl-2-methylthiomethylcyclohexa-3,5-dien-1-imin um.

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Methylthiomethylation of anilines and phenols, III: Preparation of N-aryl-S,S-dialkylsulfimides

The synthesis of a number of N-aryl-S,S-dialkylsulfimides by reaction of anilines with sulfoxides in presence of P₄O₁₀ and triethylamine is given. This series includes compounds with CH₃-, CH₃SCH₂-, CH₃O-, Cl-, Br- and nitro-groups attached to the aromatic nucleus, resp., and with CH₃-, C₂H₅-or–(CH₂)₄-groups on the sulfur atom. The sulfimide obtained from mesidine is rearranged in formal analogy to aSommelet-Hauser rearrangement to 2.4.6-trimethyl-2-methylthio-methylcyclohexa-3.5-dien-1-imine.

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Als 1. Mitt. soll gelten:P. Claus, Mh. Chem.99, 1034 (1968).

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2. Mitt.:P. Claus undW. Vycudilik, Tetrahedron Letters1968, 3607.     

Is the non-physical states conjecture valid?

The canonical quantization for N = 1 supergravity in the context of gravitational minisuperspace described by Gowdy T ³ and Bianchi class A cosmological models is analyzed in order to search for physical states. There are indeed physical states in the minisuperspace sector of the theory. This fact entails that the non-physical states conjecture has a restricted validity, and in consequence it cannot be considered a general result.     

Ketendithioacetal-S-imide

Starting from 2-isopropylidene-1,3-dithiane, various ketene-dithioacetal-S-imides have been prepared and characterized by¹H- and¹³C-NMR spectra.

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Ketendithioacetal-S-imideKurze Mitteilung

     

Ab initioSTO-3G optimization of planar,perpendicular, and twisted molecular structures of biphenyl

The complete molecular structure of biphenyl, characterized by 12 independent parameters, has been derived by ab initio gradient techniques using a STO -3G basis set for coplanar, perpendicular, and minimum energy conformations with the constraint of planar phenyl ring units and a C₂ symmetry axis along the CC interring bond. The minimum torsional angle obtained was ? = 38.63° with torsional energy barriers of 8.59 and 10.04 kJ/mol for ? = 0° and ? = 90°, respectively.