Georges Vass

STEREOSELECTIVE SYNTHESIS OF INOSITOL MONO, BIS AND TRISPHOSPHATE ANALOGUES FROM 6-DEOXY-D-INOSITOL PRECURSORS

Abstract The synthesis of opticaly pure deoxy- myo -inositol mono, bis and trisphosphate analogues is described from 4- O -benzyl-2,3-di- O -cyclohexylidene-6-deoxy- myo -inositol and corresponding 1,5 epimer chiro -inositol. These precursors, which derive from galactose, are used to accede to a variety of cyclitol intermediates employing protection/deprotection sequence. The phosphorylation procedure was performed to produce free and original substituted phosphate derivatives aimed to be incorporated through the lipidic cell membrane for in vivo evaluation.

Synthese de sucres a chaine allongee heptose et octose par c-acylation nucleophile

Abstract The synthesis of extended chain; heptoses and octoses was achieved by nucleophilic C-acylation using carbanions derived from 1,3-dithiane 1 and 2-methyl-1,3-dithiane 10 on 1,2:3,4-di-O-isopropylidene-α- d -galacto-1, 5-hexodialdopyranose 2 . The diastereoisomeric products 3 and 4 or 11 and 12 are formed in different proportion according to the solvent used. 11 was transformed by azidolysis into dithiepane derivatives 14 , 15 and 16 . From the intermediate 12 , the diol 18 , a precursor of lincosamine, was obtained.

Stereoselective synthesis of myo-inositol-1,3,4,5-tetrakisphosphate analogues from 6-deoxy d-inositol precursors

Abstract The synthesis of 6-deoxy-D-myo-inositol-1,3,4,5-tetrakisphosphates is described. The access to opticaly pure Ins(1,3,4,5)P4 analogues was carried out from deoxy myo inositol precursors derived from d -galactose. Modification of Ins(1,3,4,5)P4 analogues by lipophilic substituents has been investigated in order to produce neutral phosphate derivatives aimed to be incorporated in cell membrane for in vivo evaluation.

Condensation de D-glycosylamines avec des protéines

Abstract 4- O -β- D -Galactopyranosyl-α,β- D -glucopyranosylamine (lactosylamine), β- D -gluco-, α- and β- D -manno-pyranosylamines were bound to the carbodiimide-activated groups of lysozyme. Of the 11 free carboxyl groups of the protein, ≈3 were substituted by α,β-6-lactosylamine, and ≈2 by the monohexo-sylamines. One of the 4 glycopeptides isolated from the tryptic digest of the lysozyme-lactosylamine conjugate was identical to synthetic l- N - L -leucinoyl-4- O -β- D -galactopyranosyl-β- D -glucopyranosylamine, indicating the substitution of the carboxyl group of the C-terminal leucine residue. The isolation of a glycopeptide containing the aspartic acid residue in position 117 indicates that the second α,β-lactosylamine residue is linked to the carboxyl group of this amino acid. Both of the 2 other glycopeptides contain the same free carboxyl groups (one glutamic and two aspartic acid residues in positions 35, 48, and 52, respectively). The third α,β-lactosylamine residue seems to be linked to one of these carboxyl groups.

Nucleophilic displacement of carbohydrate primary halides with lithio-1, 3-dithiane

Aus den beiden 5-funktionellen Ribofuranosiden (Ia) und (Ib) erhalt man mit 2-Lithio-1,3-dithian (II) das Kondensationsprodukt (III), das zum Aldehyd (IV) verseift und dann zum Carbinol (V) reduziert wird.

Méthode générale de synthèse d'hydrates de carbone à chaîne ramifiée, constituants d'antibiotiques glucidiques

Summary Biological C -acylation (figure 1), can be simulated in vitro by reactions of 2-lithio-1,3-dithian and related carbanion systems on readily available carbohydrate substrates. Treatment of the ketones 3 and 10 with carbanions 1 and 2 yielded 4, 5 and 11, 12 , respectively. These highly functionalised branched dithianyl and methyl-dithianyl derivatives were transformed — employing standard procedures — to the desired carbohydrates 6, 7, 8 and 13, 14 , having as a branched chain: CHO, CH 2 OH, COCH 3 and CH 2 CH 2 groups.

Synthese de cetoses a chaine ramifiee dans la serie du d-fructose et du d-psicose

Abstract Stereospecific synthesis of branched-chain 3-C-formyl, 3-C-hydroxymethyl and 3-C-methyl derivatives of d -psicose have been achieved via nucleophilic C-acylation by means of the 1,3-dithian carbanion of 1,2:4,5-di-O-isopropylidene-β- d -erythro-hexo-2,3-diulo-2,6-pyranose 1. Addition of nitromethane to 1 led to d -psicose and d -fructose derivatives 8 and 9.

The Ramirez dioxaphospholen condensation: new access to branched-chain sugars

The product of condensation of 2,3-O-isopropylidene-D-glyceraldehyde with 4,5-dimethyldioxaphospholen was hydrolysed to a free sugar which was converted by acidified methanol into a mixture of glycosides of 1-deoxy-3-C-methyl-D-ribo-hexulose.

NUCLEOPHILIC DISPLACEMENT OF CARBOHYDRATE PRIMARY HALIDES WITH LITHIO-1,3-DITHIANE

Aus den beiden 5-funktionellen Ribofuranosiden (Ia) und (Ib) erhalt man mit 2-Lithio-1,3-dithian (II) das Kondensationsprodukt (III), das zum Aldehyd (IV) verseift und dann zum Carbinol (V) reduziert wird.

Synthesis and X-ray crystallographic studies of dithiepan derivatives of carbohydrates

Nucleophilic addition of 2-lithio-2-methyl-1,3-dithian to the dialdehyde (2) gives the two diastereo-isomers (3) and (7) was transformed into a new class of carbohydrate dithiepan derivatives (11)–(13).