Synthesen und pharmakologische Eigenschaften von 2,2-Dialkyl-5-aryl-3-pyridylpyrrolidinen

Syntheses and Pharmacological Properties of 2,2-Dialkyl-5-aryl-3-pyridylpyrrolidines Reaction of the photochemically generated benzonitrile methylides 2 with vinylpyridines yields 2-aryl-4-pyridyl-1-pyrrolines 3. Depending on reduction methods, the compounds 3 are selectively transformed to the corresponding cis- or the trans-substituted pyrrolidines 10 or 11 , respectively. Furthermore, a non-photochemical synthesis has been developed: the easily available nitro-ketones 8 provide through reductive cyclization the pyrrolines 3 or directly the pyrrolidines 11. Twenty-seven compounds of types 10 and 11 have been evaluated in the writhing, hot plate and kaolin tests; especially the cis-pyrrolidines 10 exhibit a valuable antinociceptive activity. Some of the pyrrolines and pyrrolidines have been separated into their enantiomers, which are easily interconverted.     

The role of 2,3-dimethylene-1, 4-cyclohexadiyl diradical as a reactive intermediate in some rearrangement reactions

Quantum chemical CI calculations with the semiempirical MO method SINDO1 are performed to study the rearrangement reactions of 1,2,6,7-octatetraen, 2,3-dimethylenebicyclo(2.2.0)hexane, 3,4-dimethylene-1,5-hexadiene and bicyclo(4.2.0)octa-1,5-diene. It is shown that the most favorable pathway of each of these six rearrangements involves the 2,3-dimethylene-1,4-cyclohexadiyl diradical as an interceptable intermediate. Two further intermediates, 1,2-divinyl-1-cyclobutene and 1,2-divinylylcyclobutane appear, but the latter with little importance. Energies and geometries of the four reactants resp. products, the three intermediates and twelve transitions states are presented. The mechanism of the rearrangements is discussed.     

Thermal and Photochemical Oxetane Formation. A Contribution to the Synthesis of Branched-Chain Aldonolactone

Derivatives of 2-C-branched-chain erythrono-1,4-lactones of the types 1 have been synthesized under reductive conditions using DIBAL from the oxetane 2 , which is easily accessible from diethyl mesoxalate ( 4 ) and 2,2-diisopropyl-1,3-dioxole ( 3 ) in high yield by means of a catalytic cycloaddition. Similarly, 2 rearranges in presences of AlMe₃ under formation of an erythronolactone with an additional branching at C(4). The corresponding oxetanes 7–9 from ethyl pyruvate ( 5 ) and ethyl trimethylpyruvate ( 6 ), respectively, have been studied with regard to their reductions yielding building blocks of branched-chain sugars.     

Theoretical Foundations Of Purely Semi-Empirical Quantum Chemistry. III. Repulsion Integrals

Results of ab initio calculations of correlation energies are used to estimate the correlation contribution to true repulsion integrals γpq. The one-center true γpp and the distance dependence of the true γpq are shown to be in semi-quantitative agreement with the empirical resonance integrals used in pi-electron theories. The relationship between the true γpp and the difference between true molecular ionization potentials and electron affinities is also discussed.     

Rotation von zweiatomigen Dipolmolekülen in starken elektrischen Feldern

The motion of a rigid rotator in an electrical field is well known for small fieldstrengths where it is identical with the second-order perturbation of the Stark effect. At large fieldstrengths, the rotator becomes almost fixed about the field direction and its levels coincide with those of an harmonic oscillator. In this paper the energy levels are calculated by diagonalization for the intermediate region and its deviation from the two limiting cases is briefly discussed.