J.P. Alazard

Synthesis of Tricyclic Phenylpyrrole Lactams, New Models of Antitubulin Agents

Abstract The tricyclic lactams 3 and 4 having a phenylpyrrole framework have been prepared from the arylpyrroles 5 and 16 respectively. These structural analogs of rhazinilam 1 present, like the latter, an interesting antitubulin and cytotoxic activity.

Synthèse de cyclopenta [C] tetrahydropyridines, précurseurs d'alcaloïdes monoterpéniques

Abstract An efficient synthesis of cyclopenta [c] pyridines 2 , precursors of monoterpenic alkaloids, through regioselective formylation reactions, is described.

Intramolecular radical coupling of a phenolic enolate: Oxidative fragmentation of the spirodiketone intermediate

Abstract Ferricyanide oxidation of the dianion of the phenolic δ-diketone 6b in basic conditions effects intramolecular radical coupling to form the spirocyclic diketone 7 which leads to the hydroxy tetralone 8 via an oxidative fragmentation process.

Photooxydation d'un aminodiene et d'aminodiene-boranes

Singlet oxygen photooxidation of dieneamine 1 and dieneamine-boranes 1′ followed by reduction leads to aminoketols 14, 16 and aminoketol-boranes 14′ respectively; these products are precursors of monoterpene alkaloids.

Régiosélectivité d'oxydation de diènes et triènes hétérocycliques

Resume Ozonolysis and oxidation of triene 2 and diene 3 are reported for an oxidative ring opening allowing the synthesis of secoiridoids precursors.

Action de l'eau oxygénée et de l'acide p-nitroperbenzoïque sur des imines, des oxazirannes et des nitrones cycliques stéroïdiques dérivés de la conanine

Abstract Hydrogen peroxide and a peracid react with pyrrolidinic imines, oxaziridines and nitrones of the steroidal series, to give α-hydroxylated nitrones, α-peroxyimines, hydroxylactones or hydroxamic acids. Analogies and differences between reactivities of both oxidants are shown. Thus, a peracid oxidizes a nitrone as well as an oxaziridine, whereas hydrogen peroxide which oxidizes a nitrone, by contrast, deoxygenates an oxaziridine. Differences appear also, depending on the structure of the intermediates formed which carry either hydroperoxide or perester groups. The presence of a better leaving group in the latter case may modify the course of reactions effected on a α-hydroxylated nitrone or imine. Furthermore the acylation of an aldonitrone facilitates its oxidation and leads with a peracid to an O-acylhydroxamic acid protected from further oxidation.

Synthèse stéréospécifique de la (±) épi-7,7a técomanine

Abstract The stereospecific synthesis of the (±) epi-7,7a tecomanine has been achieved by two stereospecific reactions starting from an amino diene N-borane.

A simple total synthesis of viburtinal

Viburtinal (2) has been synthesised from 2-cyclopentadienylpropanol (3)via the dihydrocyclopenta[c]pyran (1c), which was itself prepared via regioselective formylation.

PROPRIETES CHIMIQUES DES α-HYDROXYNITRONES CYCLIQUES: ACTION DU BOROHYDRURE DE SODIUM, DU CHLORURE DE BENZOYLE ET DE p-TOLUENE SULFONYLE. SYNTHESE PARTIELLE DE DERIVES DU PREGNANE FONCTIONNALISES SUR LE CARBONE-18

Abstract Pregnane derivatives with different functions on C-18 and C-20 are obtained from the pyrrolinic isomeric steroidal hydroxynitrones 2 and 3 by reaction with sodium borohydride and with acid chlorides. In particular, the benzoylation of hydroxynitrone 3 leads to pregnane-18-al-20-one with the carbonyl group at C-20, protected as its oxime ester. This enables selective oxydation and reduction of the free aldehyde at C-18. Resume L’action du borohydrure de sodium et des chlorures d’acide sur les hydroxynitrones pyrroliniques steroidiques isomeres 2 et 3, permet d’acceder a des derives du pregnane diversement fonctionnalises sur C-18 et C-20. En particulier, la benzoylation de l’hydroxynitrone 3, conduit a la pregnanal-18 one-20 avec le carbonyle en C-20, protege sour forme d’ester d’oxime 20, ce qui permet une oxydation et une reduction selective de la fonction aldehyde libre en C-18.