Dérivés de sucres benzimidazoliques et benzothiazoliques

Benzimidazole and benzothiazole sugar derivatives Simple aldehydosugars such as 1 or 2 , by reaction with o-phenylenediamine, gave the corresponding benzimidazoles 3 and 4 . Whereas the unperturbed α, β-unsaturated aldehydosugar D gave the benzodiazepine E upon treatment with o-phenylenediamine, the formyl-bearing alkenyl acetals 5 and 8 led, in the same conditions, to the benzimidazoles 6 and 9 respectively or, on reaction with o-aminothiophenol, to the benzothiazoles 7 and 10 respectively. This difference in reactivity is explained by the electrondonor ability of the oxygen atom of the alkenyl acetal function as shown by the ¹³C-RMN. spectra.     

Analogues azotés de dérivés de l'acide orotique

The synthesis of two new types of compounds with 3-oxo-5-thioxo- and 3,5-dithioxo-6-ethoxycarbonyl-2,3,4,5-tetrahydro-1,2,4-triazines are described. Their reactivity towards alkylating reagents and towards hydrazine has been studied.     

Radicaux libres dérivés de sucres. V. Dérivés d'osamines N-hydroxylées et composés voisins Communication préliminaire

Free sugar radicals. V. Deoxyhydroxylaminosugar derivatives and related compounds We describe several synthetic routes to deoxyhydroxylaminosugar derivatives of the type Glyc-N(OH)-R where Glyc stands for a sugar moiety linked by any of its C-atoms except the anomeric one and R for one of the following substituants: H-atom, acyl, phosphoryl groups, aminoacid or sugar residues. Compounds of the above structure are potentially close analogs, homoisosteres, ? NOH? replacing ? O? , of biochemically important molecules. Under aerobic conditions, solutions of these derivatives contain minute concentrations of the corresponding nitroxide radicals which do not decrease significantly the resolution of the NMR. spectra but render these compounds usable as a new kind of spin labels. Spectroscopic properties (¹H-NMR., ¹³C-NMR., ESR.) of some of these compounds are reported.     

Dérivés C-glycosyliques XXIII. Radicaux libres stables dérivés de sucre Communication préliminaire

Treated with 2,3-dimethyl-2,3-bis-(hydroxylamino)-butane, aldehydo-dialdofuranoses ( 1 ) gave a mixture of two compounds: a 1,3-dihydroxyimidazolidine ( 2 ) and a 1-hydroxyimidazoline ( 3 ). Oxidation (PbO₂) of compounds 3 gave stable free radicals having the structure of 2-C-Glycosyl-4,4,5,5-tetramethylimidazolines 1-oxyl ( 4 ), whereas 2-C-Glycosyl-4,4,5,5-tetramethylimidazolines 3-oxide 1-oxyl ( 5 ) were formed by oxidation of 2 . The ESR. spectra of compounds 4 and 5 establish the structure of the imidazoline part of these radicals and provide informations on the sugar moiety.     

Dérivés C-Glycosyliques XXXII. Synthèse de dérivés spiro-C-glycosylidéniques par cyclisation nucléophile. Communication préliminaire

C -Glycosylic derivatives XXXII. Synthesis of spiro-C -glycosylidenic derivatives via nucleophilic cyclization. On treatment with compounds bearing two nucleophilic groups as ethylenediamine, o-phenylenediamine or their monooxa or monothia analogues, 1,2:5, 6-di-O-isopropylidene-α-D -ribo-hexofuranos-3-ulose gave with excellent yields the corresponding spiro-C-glycosylidenic derivative; for example, when using o-phenylenediamine, a spirobenzimidazoline ( 5 ) was obtained. The latter compound underwent, on oxidation, a ring expansion to a morpholinobenzimidazole ( 8 ). Spirobenzodiazepines, spirobenzooxazepines and spirobenzothiazepines were formed when applying the same type of cyclization reaction to 3-C-acetylmethylene-3-deoxy-1,2:5,6-di-O-isopropylidene-α-D -ribo- and α-D -xylo-hexofuranoses.     

Triazènes et benzotriazines dérivés de sucres

Sugar triazenes and benzotriazines Several triazenylsugars have been prepared, generally in good yields, by treating an amino sugar with a substituted benzenediazonium salt. The triazenylsugars bearing a hydrogen atom on the triazenyl group are acetylated on the nitrogen atom closest to the glycosyl moiety (N(1)), even when the proton exchanged sites between N(1) and N(3). When an acetyl or a methoxycarbonyl group was present in the ortho position of the benzene ring cyclization took place leading to a 3,4-dihydro-4-methylidene-1,2,3-benzo[d]triazine or a 3,4-dihydro-1,2,3-benzo[d]triazin-4-one respectively.     

Dérivés C-glycosyliques. VII. Synthèse et réactions de nitrones dérivées de sucres. Communication préliminaire

The syntheses of three types of sugar nitrones (aldonitrone, ketonitrone and α-β unsaturated aldonitrone) are described. On 1,3-dipolar cycloaddition with phenylacetylene, the aldonitrone gave two Δ₄-isoxazolines epimeric at the new asymetric carbon, while the same reaction on the ketonitrone led to a spiro-Δ₄-isoxazoline. The reaction of these nitrones with carbon nucleophiles like phenylethynylmagnesium bromide constitutes a novel chain-extension reaction in carbohydrate chemistry.     

Radicaux libres dérivés de sucres. Partie. VII. Analogues de nucléosides marqués par un spin. Communication préliminaire

Sugar Free Radicals. VIII. Spin-Labeled Nucleosides Analogs A series of 5′-deoxy-5′-hydroxylamino derivatives of adenosine and uridine have been prepared by reduction of the corresponding oxime or nitrone. ‘Second generation’ 3′-deoxy-3′-N-aryl(or N-alkyl) hydroxylamino-β-D -xylofuranosyluracils have also been synthesized by a one-pot reaction including the following elementary steps: deblocking of the starting material, reduction of the 3′-deoxy-3′-oximinouridine, condensation of the resulting hydroxylamine with an aldehyde, reduction of the nitrone formed. The deoxy-hydroxylaminonucleosides oxidized spontaneously in the air (or in presence of traces of PbO₂) to give the corresponding nitroxide free radicals, ESR spectra of which furnished useful informations on their structures. Some of these modified nucleosides bore notable cytotoxic or antiviral activities.     

Stéréochimie de β-diols et de leurs dérivés cycliques—VII. Calcul empirique des déplacements chimiques en série dioxannique. Application a l'analyse conformationnelle de dérivés alkyles

The empirical calculation of chemical shifts of methyl-1,3-dioxans leads to consistent results. Deviations from the experimental value are correlated with ring deformation. This method is applied to 4 or 6-ethyl, -isopropyl and tertiary butyl-1,3-dioxans. With no substituent at C5, the 4-tertiary butyl group causes no more deformation than at the 2 or 5 position. Interactions of this group with one or two methyl groups at C5 are examined.     

Spectrométrie de Masse d'Hétérocycles. VIII—Edude de Dérivés du Dioxasilolanne-1,3,2

The fragmentation mechanisms of 1,3-dioxasilolane have been investigated. These fragmentations lead principally to ‘silyl’ ion formation, or involve cleavage of the bonds α and β to the silicon as for hydrogen migrations.     

Synthèse de dérivés de la benzo[c] quinolizine

The introduction of polar groups in planar polycyclic systems, for the purpose of studying their intercalating action, has been realized in the benzo[c]quinolizinium series. A functionalizing synthesis has been developed from 2-picolyl-and quinaldyllithium. Intermediate ketones or imines were cyclized by a quaternization reaction involving a concerted process. Structure and physico-chemical features of the compounds prepared were studied.     

Dérivés de désoxy-hydroxylamino-sucres et radicaux libres diglycosylnitroxydes correspondants. Communication préliminaire

Deoxy-hydroxylamino-sugar Derivatives and Corresponding Diglycosylnitroxides Radicals A number of sugar aldonitrones, including C,N-diglycosylnitrones, and ketonitrones have been treated with Grignard reagents or cyanide anion leading to the corresponding deoxy-hydroxylamino-sugars. On oxidation (air, H₅IO₆ or PbO₂), these compounds gave the corresponding nitroxide radicals whose ESR. spectra are reported. Analogues of disaccharides, in which the interglycosidic O-bridge is replaced by a hydroxyimino group, have been obtained by reacting a partially blocked sugar bearing a free hemiacetal group either with a deoxy-hydroxylaminosugar or with hydroxylamine, followed by reaction with an aldehydosugar and a reducing agent (NaBH₄). These reactions represents the key synthetic steps for the oligosaccharide-type synthesis of deoxy-hydroxyimino-oligosaccharides. Their oxidation yielded the corresponding nitroxide radicals whose ESR. spectra gave information on the conformation about the ‘interglycosidic’ bridge. This type of compounds should constitute useful spin markers for biological studies.     

Dérivés diglycosyliques. Communication préliminaire

Diglycosyl Derivatives. Preliminary communication Novel types of diglycosyl compounds, some of them bearing a resemblance to natural di- or tri-saccharides are described: a diglycosyldiyne ( 1 ), a diglycosylthiophene ( 2 ), a diglycosylaziridine ( 3 ), a diglycosyldioxolane ( 4 ), as well as six C,N-diglycosylnitrones, 9b–9f and 14 . These C,N-diglycosylnitrones, on treatment with an acetylenic Grignard reagent, led to the expected acetylenic diglycosyl-hydroxylamine 11 , whereas diglycosylisoxazolines (f. ex. 10 ) were obtained when these nitrones underwent 1,3-dipolar cycloaddition to acetylenic compounds.     

Préparation de dérivés de sucres acétyléniques terminaux et d'acides ynuroniques par réaction de Wittig. Note de laboratoire

Synthesis of Terminal Acetylenic Sugars Derivatives and Ynuronic Acids Derivatives by Use of a Wittig Reaction The method described for the preparation of terminal acetylenic sugars presents two advantages over earlier procedures: no new asymmetric center is created and the chain can be extended by one or more C-atoms. The method also allows preparation of ynuronic acids. The aldehydosugars derivatives 1–7 gave in good to excellent yields the corresponding gem-dibromoenoses 8–14 from which either the terminal acetylenic sugars derivatives 15–21 or the ynuronic acids 22–24 were easily prepared. A few examples of 1,3-dipolar cycloadditions (leading to 28–30 ) with these acetylenic sugar derivatives are also described.     

Synthèse de dérivés indoliques substitués in 7

The synthesis and some aspects of the chemical reactivity of 7-acetyl-, 7-benzoyl- and 7-bromoindoles are described.     

Spectres ir de quelques dérivés 3-acyl de la coumarine

The IR spectra of sixty-nine coumarin-3-acyl derivatives have been recorded and analysed in the region 4000-660 cm⁻¹ and 4000-400 cm⁻¹.

Band assignments are proposed as far as possible. Some absorption bands are characteristic for the examined coumarins and can be used in recognizing and differentiating a coumarin structure in an unknown compound.