Christiane Kan-Fan

Modification de la reaction de polonovsky : Action de l'anhydride trifluoroacetique sur un aminoxyde

Resume The reaction of trifluoroacetic anhydride on the N-oxide derived from N-methyl 5α-dihydroparavallarine 6 , leads to the immoniums 8 and 9 which can respectively be hydrolysed to furnish the ketone 2 and the secondary amine 1 , and hydrogenated to a mixture of amines 6 and 7 . This reaction has been studied with the help of NMR spectrography and the presence of an unstable intermediate 3 ′ proved.

Structure of goniomitine, a new type of indole alkaloid

The structure 1 proposed for goniomitine, an indole alkaloid isolated from the root bark of Gonioma malagasy (Apocynoceae), was inferred from an analysis of its MS, 1H 13C NMR spectral data. A biogenetic scheme is proposed to account for the formation of 1 from vincadifformine 9.

Cathenamine, a central intermediate in the cell free biosynthesis of ajmalicine and related indole alkaloids

A compound, which accumulates when tryptamine (I) and secologanin (II) are incubated with an enzyme preparation from Catharanthus roseus cell suspension cultures, was identified as 20,21-didehydroajmalicine (cathenamine)(IVa), and was shown to be a central intermediate in the enzymatic production of ajmalicine (Va),19-epi-ajmalicine (Vb) and tetrahydroalstonine (Vc).

Alcaloïdes de Vepris ampody (Rutacées)

Resume Des tiges et des feuilles de Vepris ampody H. Perr. (Rutacees) ont ete extraits et caracterises quatre alcaloides deja connus: N,N -dimethyltryptamine (1), kokusaginine (2), dimethoxy-2,4 methyl-10-acridone (3), evoxanthine (4) et du phenylacetamide (5). Trois alcaloides nouveaux, appartenant au groupe des quinolones-4, ont egalement ete isoles et les structures (6), (9) et (10) leur ont ete attribuees.

Oxydation de quelques amines tertiaires par l'anhydride chromique dans la pyridine

Resume The oxidation of several steroidal tertiary amines by chromic anhydride in pyridine leads, with various yields, to the corresponding N-formyl derivatives. In certain cases, this method is of preparative value.

Nouveaux alcaloides indoliques derives de l'aristoteline extraits d'aristotelia australasica

Abstract The structure of seven new indole alkaloids 2 , 3 , 5 , 6 , 8 , 9 and 11 derived from aristoteline 1 have been determined from 1H NMR, 13C NMR, mass spectrometry data and chemical properties. The biogenesis of these alkaloids is discussed.

Synthesis of a Novel Fused Tricyclic Quinolone system via Oxidation of 1,2,3,4-Tetrahydro-β-Carbolines.

Abstract The new pyrrolo[3,4-b]quinolin-9-one system has been synthesized via metachloroperbenzoic acid oxidation of quinolones 5 and 10 . These latter compounds were obtained by O 2 oxidation of 1,2,3,4-tetrahydro-β-carbolines. The unexpected m -CPBA oxidation has been studied in connection with the Polonovski reaction.

Guettardine, a possible biogenetic intermediate in the formation of corynanthe-cinchona alkaloids

Abstract The structure of guettardine 1, an indole alkaloid isolated from the bark of Guettarda heterosepala (Rubiaceae), was determined from an analysis of its MS, 1 H and 13 C NMR spectral data, and by a chemical correlation with dihydrocorynantheol 7. Guettardine 1 can be considered to be an intermediate between the Corynanthe and the cinchonamine groups of alkaloids which are precursors of quinine and its derivatives.

La criocerine: Nouvel alcaloide isole des tiges de Crioceras dipladeniiflorus

Abstract Seven indolic alkaloids have been isolated from the stem bark of Crioceras dipladeniiflorus . One of them is new and has been called criocerine. Its structure, 7, has been established by use of physical data and chemical correlation with [Δ 14 ]-vincamine.

The fragmentation of NN-dimethyltryptamine oxide and related compounds: a possible implication in indole alkaloid biosynthesis

A modified Polonovski reaction on NN-di-methyltryptamine oxide and related compounds leads to products of fragmentation; the possible role of this new reaction in indole alkaloid biosynthesis is emphasized.