Ingemar Kvarnström

Preparation and N.M.R. studies of pyruvic acid and related acetals of pyranosides: configuration at the acetal carbon atoms

Abstract Stereoisomeric pairs of pyruvic acid and related acetals linked to the 3,4- and 4,6-positions, respectively, of the anomeric methyl d -galactopyranosides and the corresponding acetals linked to the 4,6-positions of the anomeric methyl d -glucopyranosides have been prepared by conventional methods, and their structures have been assigned. Their 1 H- and 13 C-n.m.r. spectra have been recorded. The differences in chemical shifts obtained for stereoisomeric pairs of acetalic CH 3 groups are of sufficient magnitude to make possible the unequivocal determination of the stereo-chemistry of pyruvic acid acetals in naturally occurring polysaccharides.

Synthesis of [4,5-Bis(hydroxymethyl)-1,3-dioxolan-2-yl]nucleosides as Potential Inhibitors of HIV

The synthesis of 1,3-dioxolan-2-ylnucleosides and related chemistry is described. We have shown that 2-methoxy-1,3-dioxolane (6) reacts with silylated thymine and trimethylsilyl triflate to give the acyclic formate ester 1-[2-(formyloxy)ethyl]thymine (8) rather than 1-(1,3-dioxolan-2-yl)thymine (7). A tentative mechanism which could explain this result is discussed. On the other hand, 2-methoxy-1,3-dioxolane 13c reacts with silylated bases to give [4,5-bis(hydroxymethyl)-1,3-dioxolan-2-yl]nucleosides, thus representing the first examples of this novel class of compounds. The nature of the nucleobase and the hydroxyl protecting groups was found to have great influence on the reaction and on the stability of the nucleosides. Compounds 16 and 18 were found to be inactive when tested for anti HIV-1 activity in vitro.

Synthesis of 1D-2-O- and 1D-5-O-(α-D-galactopyranosyl)-4-O-methyl-chiro-inositol: preference for equatorial hydroxyl groups in the imidate galactosylation procedure

Abstract 1 D -2- O -(α- D -Galactopyranosyl)-4- O -methyl- chiro -inositol, identical to a galactosylpinitol previously isolated from seeds of Trifolium subterraneum , has been synthesised, together with an isomer, 1 D -5- O -(α- D -galactopyranosyl)-4- O -methyl- chiro -inositol. In both syntheses, the imidate method of galactosylation was used on inositol derivatives having one axial and one equatorial hydroxyl-group free. Good selectivity of the reagent for the equatorial hydroxyl groups was demonstrated.