Determination de structures par RMN du 1H A 400 MH : Alcaloides de tabernaemontana albiflora.

The structures of two new alkaloids of the 21-nor (+) pandolane type from the bark of $\text{Tabernaemontana albiflora}$ (Miq.) Pull. (Apocynaceae), were determined.     

Une synthese efficace et rapide de l'isobellendine,alcaloide ℘-pyranotropanique de bellendenamontana

An effective two step synthesis of isobellendine, starting from tropinone, is described.     

NMR Studies of Alkaloids. Assignment of the Configuration at C(20) in Tubotaiwine (Dihydrocondylocarpine)

Two-dimensional, high-field NMR methods are employed in confirming the relative configuration at the C(20) ethyl side-chain junction as S* in the natural alkaloid tubotaiwine (dihydrocondylocarpine).     

Total synthesis of (±)-desmethylhexahydrovallesiachotaminelactones

Total synthesis of (±)-desmethylhexahydrovallesiachotaminelactones 1a and 1b, and their isomers 2a and 2b is described. The formation of other epimeric pairs of lactones (1a and 3a, and 1b and 3b) from vallesiachotamine 4 is also described.     

Carbon-13 spin–lattice relaxation of tropane alkaloids. Anisotropic rotational motion of tropine and pseudotropine

The ¹³C spin–lattice relaxation times of tropine and pseudotropine have been measured in CDCl₃ as a function of concentration. The same relative increase in concentration serves to increase the relaxation rates much less in the region 0.9–5.0 wt.% than in the region 5.0–14.3 wt.%. The rotational diffusion coefficients have been calculated from the relaxation data using Woessner's anisotropic rotational diffusion model. Reorientation of both molecules is shown to be moderately anisotropic. The principal axes of the rotational diffusion tensor in the symmetry plane of both molecules are rotationally shifted from the principal axes of the moment of inertia tensor of the free molecules, and the main rotational axis is parallel with a line passing through the centre of mass of the molecule and the nitrogen atom.     

Novel applications of the modified polonovski reaction. A biomimetic synthesis of quinuclidines.

Suitably substituted aminoesters can be transformed to the corresponding α-aminonitriles and in the case of piperidino-acetic ester derivatives, into the biochemically important quinuclidine ring system.