Synthèse de l'amino-4 formyl-3 méthyl-6 pyridazine

The 4-amino-3-formyl-6-methylpyridazine, a new reagent in the pyridazine series, has been synthesized by two different routes. For that purpose some new ortho-substituted compounds of pyridazine have also been prepared.     

Synthèse de l'ériodermine

Synthesis of Eriodermin The total synthesis of eriodermin (=2,7-dichloro-4-formyl 3-hydroxy-8-methoxy-1,6-dimethyl-11H-dibenzo[b,e] [1,4]dioxepin-11-one) is described.     

Synthèse de l'évernine

Synthesis of Evernin Two syntheses of the depside evernin 6 are described. Condensation of methyl acetoacetate and methyl crotonate followed by aromatization and reduction with Raney-Ni led to methyl orsellinate (3) . The condensation of everninic acid (4) , obtained by partial methylation of 3 and saponification of the methyl ester, with methyl 2, 4-dihydroxy-3, 6-dimethylbenzoate (methyl β-orcin carboxylate) (5) in presence of cyclohexylcarbodiimide gave evernin ( 6 ). In a second syntheis methyl dihydroorsellinate (1) was regiospecifically converted into its 4-methyl enol ether and aromatized via the benzene selenenyl derivative to yield methyl evernate (7) . Benzylation followed by saponification gave the free acid 8 . Methyl β-orcin carboxylate (5) was synthesized in an analogous way from methyl 3,6-dimethyl-2,4-dioxocyclohexanecarboxylate. Condensation of 8 with the methyl ester 5 by treatment with trifluoroacetic anhydride in toluene yielded 9 , which could be converted into evernin ( 6 ) by hydrogenolysis of the benzyl ether.     

Synthèse de la diméthyl-4,4-dihydrofuranedione-2,3

4,4-Dimethyl-dihydro-2,3-furanedione ( 4 ), an intermediate in the synthesis of (+)-D -pantothenic acid, is obtained in good yield from readily available substances such as isopropyl chloride, diethyl oxalate and formaldehyde, without oxidative conditions.     

Synthèse du virensate de méthyle

Synthesis of Methyl Virensate The synthesis of methyl virensate (=methyl 4-formyl-3,8-dihydroxy-1,6,9-trimethyl-11-oxo-11H-dibenzo-[b, e][1,4]dioxepin-7-carboxylate; 18 ) by the condensation of the substituted β-orcinol and orcinol units 9 and 10 followed by formylation and demethylation of the depsidone 13 is described.     

Synthèse du mèthyl-1 diformyl-2,3 pyrrole,de la méthyl-1 pyrrolo[2,3-d] pyridazine et de la méthyl-1 oxo-6 (6h)cycloheptatrieno[b] pyrrole

This communication describes the synthesis of l-methyl-2,3-diformylpyrrole. This new compound is used to prepare a new heterocycle, l-methylcyclohepta[b]pyrrol-6-one and thus allows a new synthesis of l-methylpyrrolo[2,3-d]pyridazine.     

Synthèse d'hétérocycles en catalyse par transfert de phase

A general study of the chemical behavior of heterocyclic anions, dianions and dianionic reagents under phase transfer catalysis conditions allowed us to synthesize various heterocyclic compounds such as imidazo[2,1-b]thiazole and derivatives; imidazo[2,1-b]thiazine and imidazo[2,1-b]benzothiazepine. Reaction conditions e.g., catalyst, solvent, temperature, etc., are indicated.     

Synthèse de pyrimidines et purines adamantylées par alkylation régiosélective directe,en catalyse par transfert de phase

The use of 1-adamantyl bromomethyl ketone, under phase transfer catalysis conditions permits the regioselective N₁ alkylation of uracil and thymine,the N₁,N₃ dialkyl derivatives. The observed selectivity is discussed in relaxation with the structure of the alkylating agent.     

Synthèse de dimethyl-2,2 chromannediones-3,4: Condensation avec les ortho-diaminopyridines

2,2-Dimethylchromanedoines have been prepared by oxydation of corresponding chromanones with isoamyle nitrite. In the major cases, the monoketones have been isolates by reaction of 3-methyl-2butenoic acid with substituted phenols in the presence of polyphosphoric acid. The condensation of chromanediones with orthor-diaminopyridines gives an isomeric mixture of benzopyranopyridopyrazines.     

Synthèse partielle et propriétés oncostatiques des pseudo-tubulosines,analogues de l'émétine et de la tubulosine

Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and Tubulosine Pseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet-Spengler or Bischler-Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.     

Synthèse de l'amino-3 azétidine

The synthesis of a novel heterocyclic compound, 3-aminoazetidine as a potential pharmacophore belonging to piperazine or 4-aminopiperidine structural classes, is described. The method is based on a phase-transfer catalysed nucleophilic alkylation of potassium phthalimide.     

Double inversion de fréquences de protons méthyléniques par interaction 1-3 syn-diaxiales. Mise en évidence par RMN haute résolution

The high field NMR spectra of two 2,3,6-trihalogeno-2-methylcyclohexanones show a double inversion of chemical shifts for methylene protons. This anomaly is explained by 1-3 syn-diaxial interactions.     

Synthèse de sucres aminés ramifiés. IV Synthèse de quelques dérivés nouveaux par l'intermédiaire d'une hexose-spiro-aziridine

Treatment of 3-C-cyano-1,2:5,6-di-O-isopropylidene-3-O-(toluene-p-sulfonyl)-α-D -allofurannose with AlLiH₄ yields a sugar-spiro-aziridine and a branched chain sulfonamide. Reaction mechanisms are briefly discussed and the configurations of the products obtained are proved by chemical reactions. With hydrogenation, the spiro compound is opened to a branched chain amino sugar with the same tertiary carbon as in vancosamine. Several derivatives of this new compound are described: the 6-deoxy sugars in series L and D and the pentose resulting from its oxidation by periodic acid. The conformation around C(4)–C(5) bond is deduced for three compounds from NMR. data.     

Etude de la réactivité de la fonction carbonyle avec le cétène en présence d'un alcoxyde de titane. 1ère communication. Nouvelle méthode de synthèse de β-hydroxyesters

A new synthesis of β-hydroxyesters involving a reaction between a carbonyl compound, ketene and an alkyl-orthotitanate is described. The following carbonyl compounds have been studied: aldehydes, ketones, α-diketones, α- or γ-ketoesters. A reaction mechanism is proposed.     

Synthèse et caractérisation de bis acridines pontées en positions 2, 3 ou 4

The preparation of 2,2′, 3,3′ and 4,4′-bridged bisacridines is described. The method consists in the acylation of 2m 3, or 4-aminoacridines in acetone, as the solvent. Ten bisacridines were isolated and characterized by their ¹H and ¹³C nmr parameters. Some of these were tested as potential intercalating agents, but none has shown any activity from this point of view.     

Synthèse de polyéthers polycycliques. 1 Stéréosélectivité de l'hétérocyclisation d'alcools tétrahydrofurfuryliques γ,δ-éthyléniques par les sels mercuriques

The intramolecular oxymercuration of the l-(2-tetrahydrofuryl)4-penten-1-ols (5) by merruric salts followed by reductive demercuration affords the 2-methyl-5-tetrahydrofuryltetrahydrofuran (9) as a mixture of cis and trans isomers in good yields. By using mercuric acetate, each isomier threo 5a and erythro 5b gives the trans isomer, 9d and 9b, respectively, as the major products. On the other hand, cyclizations carried out with mercuric chloride are not stereoselective.