3-azido-3-deoxy-2,2 ': 5,6-di-O-isopropylidene-2-C-hydroxmethyl-D-gulono-1,4-lactone

The crystal structure of azidolactone, C13H19O 6N3, was analyzed. The compound formed by SN2 displacement of the trifluoromethanesulfonate with sodium azide, is the first example of a branched β-sugar amino acid scaffold. The sample was crystallized from diethyl ether by inward diffusion of n-hexane to give lath-shaped colourless crystals. The X-ray crystallographic analysis of the product of the reaction showed the presence of inverted azide

2,3 : 5,6-di-O-isopropylidene-2-C-hydroxy-methyl-D-talono-1,4-lactone

The title diacetonide, C13H20O7, readily available in quantity from D-tagatose, is likely to be a useful carbohydrate starting material. The current structure analysis resolves any ambiguities arising from the synthetic route over the configuration at the new chiral centre and the size of the lactone ring, but otherwise shows no unusual features. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved

6R- and 6S-6C-Methylmannose from D-mannuronolactone. Inhibition of phosphoglucomutase and phosphomannomutase: agents for the study of the primary metabolism of mannose

The syntheses of 6S-3 and 6R-6 6C-methylmannoses rely on opposite and highly stereoselective reductions of fully and partially protected ketones derived from D-mannuronolactone, respectively. Reduction of the silylated ketone 2 by sodium borohydride was accompanied by complete migration of the silyl protecting group to the new stereogenic centre; the silyl migration was suppressed when the reduction was conducted in the presence of cerium(III) chloride. Both epimers were good inhibitors of phosphoglucomutase and phosphomannomutase, and are specific inhibitors of phosphohexomutases. This work confirms that 6C-alkylhexoses provide a valuable set of compounds with good bioavailability for the study of enzymes involved in the primary metabolism of sugar phosphates. The X-ray crystallographic analysis of 7- deoxy-2,3:5,6-di-O-isopropylidene-α-L-glycero-D-manno-heptofuranose 16 is reported

Spirodiketopiperazines of mannofuranose: carbopeptoid alpha-amino acid esters at the anomeric position of mannofuranose

Epimeric mannofuranose anomeric aminoesters are prepared from readily available azidolactones and can act as building blocks for the incorporation of mannofuranose units into peptide chains [carbopeptoids]; alternative acylating conditions allow either rapid acylation of the more stable but kinetically hindered amine or reaction with the less hindered but less stable amine to allow control of the anomeric configuration of the products. This is exemplified by coupling of the aminoesters with glycine derivatives to give dipeptide equivalents, and subsequent cyclization to spiro diketopiperazines. Anomers with the nitrogen function cis to the 2,3-diol are more stable than those with nitrogen trans; mannofuranose derivatives are more Stable than the mannopyranose isomers

Kinetic and thermodynamic azides from alpha-triflates of gamma-lactones: Intermediates for the incorporation of polyhydroxylated D- and L-alpha-aminoacids into combinatorial libraries

Displacement of α-triflates of 2,3,4-all cis-substituted γ-lactones by sodium azide in DMF gives kinetically an azide with inversion of configuration at the C-2 of the lactone; under the reaction conditions, the initially formed azide epimerises to the apparently more crowded and thermodynamically stable all cis-azide, giving intermediates which should readily allow the incorporation of polyhydroxylated amino acids into combinatorial libraries