Erzsébet Ősz

An easy access to anomeric glycosyl amides and imines(Schiff bases) via transformation of glycopyranosyl trimethylphosphinimides

Abstract The preparation and application of anomeric glycosyl phosphinimides in preparative synthesis were studied. Starting from the appropriate glycosyl azides and trialkyl or triaryl phosphines, the corresponding phosphinimides were obtained by modified Staudinger reactions. The latter compounds were readily converted into 1- N -acyl-gluco- and galactopyranosyl amines with high yields by applying activated acid derivatives or simple carboxylic acids. 1- N -Alkylidene- or arylidenephosphinimines (Schiff bases) were obtained by means of aza-Wittig reactions using aliphatic or aromatic aldehydes, respectively.

Syntheses of novel glycosylidene-spiro-heterocycles related to hydantocidin

Abstract Reaction of 2,3,4,6- tetra -O- acetyl-1-bromo-1-deoxy -β- d -galactopyranosyl cyanide (4) with thiocyanate ions results in the formation of both anomers of per-O-acetylated 1-deoxy-1-thiocyanato- d -galactopyranosyl cyanides (5a and 5b). The thiocyanate group in these products is resistant to isomerization into isothiocyanate even at elevated temperatures. The X-ray structure of 5a is consistent with the operation of an exo-anomeric effect for the thiocyanate group. Compounds 5a and 5b react with hydrogen sulfide under mild conditions to yield galactopyranosylidene-spiro-thiazolidine (8) and -thiazoline (9, 12, and 13) derivatives.

Capsoneoxanthin, a new carotenoid isolated from the fruits of Asparagus falcatus

Abstract From the ripe fruits of Asparagus falcatus capsoneoxanthin, a minor carotenoid was isolated and, based on its spectral data, identified as (all-E,3S,5R,6R,3′S,5′R)-6,7-didehydro-5,6-dihydro-3,5,3′-trihydroxy-β,κ-caroten-6′-one.

Structural background for serological cross‐reactivity between bacteria of different enterobacterial serotypes

The structure of the oligosaccharide repeating units of endotoxins from Gram‐negative bacteria is characteristic for the different serogroups and serotypes of bacteria. Detailed examination of the cross‐reactions of three enterobacterial serotypes, Proteus morganii O34, Escherichia coli O111, and Salmonella enterica sv. Adelaide O35, was performed using sensitive tests (ELISA, immunoblotting). Fine differences between the endotoxins of the bacteria were detected using silver staining of SDS‐PAGE gels and chip‐technology for the intact lipopolysaccharides (LPSs). The compositions of the O‐specific polysaccharides of LPSs extracted from the bacteria were studied, and it was proven that the three cross‐reacting bacteria contain O‐antigens built from the same monosaccharides, namely colitoses linked to glucose, galactose, and N‐acetyl‐galactosamine. The NMR and GC‐MS studies revealed that the most probable component for the cross‐reaction is the rare sugar, colitose.

Reduction of Capsorubin and Cryptocapsin

)DepartmentofMolecularPharmacology,InstituteofChemistry,ChemicalResearchCenter,P.O.Box17,H-1525Budapest(6S)-and(6R)-−Capsorubol-6-one×( (3S,3S,5R,5R,6S)-and(3S,3S,5R,5R,6R)-3,3,6-trihydroxy- , -caro-ten-6-one;8and9,resp.),(6S,6R)-and(6R,6R)-capsorubol( 3S,3S,5R,5R,6S,6R)-and(3S,3S,5R,5R,6R,6R)- , -carotene-3,3,6,6-tetrol; 11 and 12, resp.) and (6S)- and (6R)-cryptocapsol ( (3S,5R,6S)- and(3S,5R,6R)- , -carotene-3,6-diol; 5and 6, resp.) were prepared in crystalline from by the reduction ofcapsorubin ( (3S,3S,5R,5R)-3,3-dihydroxy- , -carotene-6,6-dione; 7) and cryptocapsin ( (3S,5R)-3-hydroxy- , -caroten-6-one;4)andcharacterizedbytheirUV/VIS,CD,

Novel glycosylidene-spiro-heterocycles from unprecedented solvent incorporation in Koenigs–Knorr-like reactions of C-(1-bromo-1-deoxy-β-D-glycopyranosyl)formamides

The title compounds give glycopyranosylidene-spiro-dioxolanes 3 and 4 in acetone and C-(1-methylsulfanylmethoxy-α-D-glycopyranosyl)formamides 5 in DMSO in the presence of Ag2CO3 and AgF, respectively.