Jean Lévy

On the synthesis of the oxindole alkaloid: (±)-horsfiline

Two syntheses of the title compound [(±)-1a] have been described: the first one is based upon the oxidative rearrangement of 7-methoxy- N-methyltetrahydro-γ-carboline (6a), while the second path involves a spirocyclization between 2-oxo-5-methoxytryptamine (18a) and formaldehyde

Determination of yohimbine and its two hydroxylated metabolites in humans by high-performance liquid chromatography and mass spectral analysis

The existence of at least two metabolites of yohimbine (YO) in humans is demonstrated. Combined high-performance liquid chromatographic (HPLC), NMR and mass spectral analyses permitted them to be identified as hydroxylated metabolites at the C-10 and C-11 positions. A normal-phase HPLC method allowing the simultaneous determination of YO and its main metabolite, 11-hydroxyyohimbine (11-OHYO), in biological samples is described. This assay was performed using a LiChrosorb Si 60 column and a mobile phase consisting of 0.02 M sodium acetate (pH 5)-methanol (5:95, v/v) at a flow-rate of 1 ml/min. Detection was achieved by a fluorimetric method (excitation at 280 nm and emission at 320 nm). The extraction yields of YO, 10-OHYO and 11-OHYO from plasma were 91.8, 45.3 and 17.8%, respectively, and their respective within-day reproducibilities were 3.8, 1.4 and 5.9%. The between-day reproducibility for YO at the concentrations of 1 and 10 ng/ml were 8.9 and 6.4%, respectively. The accuracy of the method for YO at concentrations of 1 and 10 ng/ml were 5.1 and 2.3%, respectively. The limits of determination of YO, 10-OHYO and 11-OHYO were 0.1, 0.5 and 1 ng/ml, respectively. The method was used in bioavailability study of YO following oral and intravenous administration in humans.

Méthylène-indolines, indolénines et indoléniniums—XIII: L'hydroxy-16 déhydro-1 vincadifformine, intérmédiaire dans le réarrangement biomimétique de la vincadifformine en vincamine

Abstract The title compound is a crucial intermediate in the biomimetic conversion of vincadifformine 1 into vincamine 7 . Its configuration at C-16 is established by a combination of chemical and spectroscopic evidence. Iodine oxidation converts 14 into the bridged lactam 18 , thus proving a β configuration for the hydroxy group at C-16. The same reaction applied to vindoline 19 gives 21 identical with one of the compounds obtained by microbiological transformation of 19 . The 13 C NMR spectra of derivatives 3 and 8 (obtained by oxidation of vincadifformine) show that oxidation proceeds with introduction of the substituent at C-16, with a β-configuration. The alcohol 3 however, posesses a different conformation due to strong hydrogen bonding with N-4.

Methylene-indolines, indolenines et indoleniniums—XII : Hemisynthese de la dehydro-14,15 vincamine et de la criocerine

Resume (-)-Tabersonine 1 was oxidised and rearranged to (+)-14,15-dehydrovincamine 5, (+)-14,15-dehydro,16-epi vincamine 6, and the rhazinilam derivative 9. Iodine and potassium iodate oxidised 5 to 14-iodo criocerine 13, Which led to criocerine 14.

Alkaloids of Alstonia lanceolata

Abstract Thirteen alkaloids were isolated from the stem bark of Alstonia lanceolata . They were lochnericine, gentianine, 10,11-dimethoxy-1-methyl-deacetylpi

Alcaloïdes des feuilles et écorces de tronc d'Alstonia odontophora

Abstract Six known indole alkaloids were isolated from the leaves and stem bark of Alstonia odontophora : vincamajine, 11-methoxy- akuammicine, quebrachidine, pleiocarpamine, antirhine, pleiocorine and pleiocraline, along with the novel bisindole, N (I′)-demethylpleiocorine.

Synthesis in the indole series viii (1): a novel approach to indoloquinolizidines through alkylation-cyclization of an enamine derived from tryptamine

Resume A short access to enamide 1 and enamine 2 from tryptamine is described. Alkylation of 2 is followed by Mannich cyclization. This new route to indoloquinolizidines is applied to a short vincamone synthesis.

Synthesis of hexacyclic indole alkaloids related to vindolinine by sonochemical cyclization

Abstract Upon treatment with sodium in THF under sonication, 19-iodotabersonine underwent cyclization to the vindolinine ring system. The yields and ratio of the diastereomers thus obtained depended on the sonication parameters.

Thermal rearrangements of some indole alkaloid derivatives

Under both static and flow thermolysis conditions, several compounds with an “aspidosperma” framework rearranged to “vinca” derivatives. Thus (-)1,2-dehydroaspidospermidine (4) rearranged to (-) gave vincane 14. Compound 6 rearranged to vincamine (13a) and 16-epi vincamine (13b) under either condition ; increasing the temperature resulted in formation of apovincamine (19) (pyrolysis) or vincamone thermolysis).

Derives 14-hydroxyles de la vincadifformine et de la vincamine

Abstract Hydroboration-oxidation of tabersonine 1 yielded as major product 14 β-hydroxy vincadifformine 9b, which was correlated with 14 β-hydroxy N(1)-methyl 2β-H, 16β-H dihydro vincadifformine 6b (previously prepared and characterised), and 14α-hydroxy vincadifformine 9a as minor product. The regio- and stereoselectivity of hydroboration-oxidation were interpreted. 9a and 9b were respectively oxidised and rearranged to the corresponding 14-hydroxy vincamines 13a and 13b. The coupling constants of H(14) on the NMR of the acetyl derivatives of 9a, 9b, 13a and 13b are consistent with an inversion of N(4) during the rearrangement leading from the vincadifformine to the vincamine skeleton.