Jeannine Tronchet

1,2-O-Isopropylide`ne-pentodialdofuranoses

Abstract 1,2- O -Isopropylidenepentodialdofuranoses having ribo , lyxo , and arabino configurations, as well as analogs having one (C-3) or two (C-3 and C-4) hybrid sp 2 carbon atoms were synthesized. The orientation of these compounds at the C-4 C-5 bond is practically independent of the modifications of the substitution at C-3. It seems to be directed by orbital factors favoring a conformer having a carbonyl group and an O-C-4 bond nearly eclipsed.

Synthèse de l'apiose et de composés voisins par des réactions de wittig

Abstract Treatment of 1,2-O-isopropylidene-α- D -glycero-tetros-3-ulofuranose (7) with cyanomethylenetriphenylphosphorane gave in excellent yield a mixture of the geometrical isomers of the corresponding cyanomethylenic derivative. After treatment with potassium permanganate, and then with sodium borohydride, this unsaturated, branched-chain sugar derivative was stereospecifically converted into 3-C-hydroxymethy]-1,2-O-isopropylidene-β- L -threofuranose. Similarly, treatment of the L -enantiomer of 7 with methylthiomethylenetriphenylphosphorane gave the expected methylthiomethylenic analogs, from which 3-deoxy-3-C-methyl and 3-deoxy-3-C-dimethoxymethyl derivatives were prepared. Wittig reactions thus allow the synthesis of branched-chain sugars bearing the side-chain on the more hindered side of the ring, compounds which are difficult to obtain by other methods.

Utilisation des constantes de couplage ge´minal pour l'analyse structurale de de´rive´s de sucres furaniques

Abstract Several derivatives of 1,2- O -isopropylidenetetrofuranoses bearing various substituents at C-3 were studied by n.m.r., and the values of the geminal coupling constant 2 J 4,4 are reported. For compounds having an sp 3 -hybridized C-3, the magnitude of 2 J 4,4 depends on the relative position of the protons of the methylene group and of the OH or OR group at C-3. When the OH (or OR) group is extra (projected along the C-3 C-4 bond, outside the H-C-4-H angle), the value for 2 J 4,4 is more negative than when this group is intra (projected inside the H-C-4-H angle). compounds having an sp 2 -hybridized C-3 show a relationship between 2 J 4,4 and the electron-withdrawing power of the substituent doubly bonded to C-3: the more electron-withdrawing is this substituent, the more negative is the coupling constant.

Ring expansions in carbohydrate chemistry: gem-azoacetates☆

Abstract On treatment with lead tetraacetate, blocked furanos-3-ulose and furanos-3-uloside p -nitrophenylhydrazones afforded the corresponding “ gem -azoacetates”. The reaction was not stereospecific, except when the starting hydrazone was blocked by a 1,2- O -isopropylidene group. Upon deacetylation of the former compounds, gem -azoalcohols of various stabilities were formed. They rearranged, either on silica gel or upon alkaline treatment, leading regiospecifically to ring-expanded 3-azapyranosic N -arylaminolactams. This regiospecific ring-enlargement reaction, which maintains the stereochemistry of every asymmetric carbon atom of the molecule and breaks the carbon chain of the starting ketose, constitutes a useful source of chirons of various sizes. In the pyranose series, the reaction was not regiospecific, affording a mixture.

Some Physico-Chemical and Biological Properties of Triazeno Sugars

Abstract Replacement of the alkyl group of l-aryl-3-alkyltriazenes with a sugar moiety did not significantly modify their tautomeric behaviour. The same replacement done on 1-aryl-3-alkyl-3-methyl-triazenes did not affect to any large extent their rotameric properties. In contrast, the most prominent biological properties, anticancer activity and toxicity, of 1-aryl-3-methyltria-zenes disappeared on replacement of the methyl group with a sugar moiety. Unexpectedly, the N-acetyltriazene 15 was highly cyto-toxic.

Methyl 2-Aza-2-deoxy-4,6-di- O -methyl-2- N -( p -nitrophenylamino)-β- D - erythro -hexopyranosid-3-ulose

All asymmetric C atoms of the title compound, C 14 H 19 N 3 O 7 , are in the R configuration. The azapyranose ring adopts a half-chair conformation with substituents in equatorial and quasi-equatorial positions. The molecular packing is fixed by hydrogen bonds involving the amino group and one of the methoxy substituents.