Claude Tapiero

Analytical methods for monoterpene glycosides in grape and wine: I. XAD-2 extraction and gas chromatographic—mass spectrometric determination of synthetic glycosides☆

Synthetic monoterpene and aromatic beta-D-glucopyranosides, beta-rutinosides and 6-O-(alpha-L-arabinofuranosyl)-beta-D-glucopyranosides and their corresponding alcohols, diluted in a synthetic solution imitating wine, were isolated and separated by selective retention on Amberlite XAD-2. The corresponding recoveries and the conditions for the direct determination of these glycosides by gas chromatography and gas chromatography-mass spectrometry after derivatization were determined. Trifluoroacetylation gave the best results but trimethylsilylation provided complementary results. The separation of some diastereoisomeric monoterpene glycosides was also examined.

Studies on the Δδ criterion for determining the anomeric configuration of ribofuranosyl nucleosides

Abstract Studies on the origin of the criterion for determination of the anomeric configuration of D -ribofuranosyl nucleosides, based on the differences in the chemical shift (Δδ) between the Me signals of the corresponding 2′,3′- O -isopropylidene derivatives, is discussed. Proof of the anisotropic influence of the aglycon group on the chemical shifts of the Me groups is given by a comparison of the chemical shifts of anomeric pairs of nucleosides having a reduced aglycon group with those of the non-reduced heterocycle. Therefore, the criterion appears to be limited to ribofuranosyl compounds having an unsaturated heterocyclic aglycon.

Synthesis and n.m.r. spectral properties of grape monoterpenyl glycosides

Abstract Several grape 6-O-(6-deoxy-α- l -mannopyranosyl)-β- d -glucopyranosides and 6-O-α- l -arabinofuranosyl-β- d -glucopyranosides having (E)- and (Z)-3, 7-dimethyl-2, 6-octadien-1-yl, (R, S)-3, 7-dimethyl-1, 6-octadien-3-yl, (R, S)-1-methyl-1-(4-methyl-3-cyclohexen-1-yl)ethyl, benzyl, and 2-phenylethyl as aglycon group, as well as such diglycosides of chromogenic 4-nitrophenol, were synthesized by two methods, one involving mercuric cyanide-catalyzed glycosylation with glycosyl halides, and the other by acid-catalyzed glycosylation with glycosyl trichloracetimidates. Their 1H- and 13C-n.m.r. spectra, especially the glycosylation shifts of the 13C-signals, were investigated.

Synthèses de 6-O-β-d-apiofuranosyl-β-d-glucopyranosides de monoterpényle

Abstract The synthetic apiosyl-glucosides having (S)-3,7-dimethyl-1,6-octadien-3-yl (linalyl); (R)-1-methyl-1-(4-methyl-3-cyclohexen-1-yl)ethyl (terpineyl); (E) and (Z)-3,7-dimethyl-2,6-octadien-1-yl (geranyl and neryl); (S)-3,7-dimethyl-6-octen-1-yl (citronellyl); benzyl and 2-phenylethyl as aglycon moiety were prepared using the stereospecific trichloroacetimidate Schmidt method. The key intermediate diholoside 1,2,3,4-tetra-O-acetyl-6-O-[(3-C-acetoxymethyl)-2,3-di-O-acetyl-β- d -erythrofuranosyl)-β- d -glucopyranose was obtained by Kochetkov glycosylation of a branched-chain tetrofuranose cyanoethylidene derivative. The NMR data (1H and 13C) of the synthetic compounds and the glycosylation shifts of the apiose moiety are reported.

Obtention de I-D-ribofuranosylade´nines

Abstract The I- D -ribosyladenines have been obtained by treatment of 5-amino-4-cyanoimidazole ( N -substituted or not) with ethyl N -(2,3- O -isopropylidene- D -ribofuranosyl)formimidate. The anomeric mixtures of the corresponding O -isoprophylidene nucleoside have been separated and the anomer fully characterized. In neutral aqueous medium, these compounds are transformed into an anomeric mixture of the corresponding 6- D -ribofuranosyladenine. In basic medium, however, anomerisation of the starting compounds to give an α,β equilibrium, in which the α anomer preponderates, takes place.