The synthesis of evernitrose and 3-epi-evernitrose

Stereoselective synthesis, structural characterization, and properties of 1,2-O-isopropylidene-3-C-(5-phenyl-1,2,4-oxadiazol-3-yl)-β-d-psicopyranose

1,2:4,5-Di-O-isopropylidene-3-C-(5-phenyl-1,2,4-oxadiazol-3-yl)-beta-D-psicopyranose 14 was synthesized stereoselectively from 1,2:4,5-di-O-isopropylidene-3-C-amidoximino-3-O-benzoyl-beta-D-psicopyranose 8 using a novel procedure. Treatment of 8 with acetic anhydride, chloroacetyl chloride, propanic anhydride, or benzoyl chloride causes the 3-O-benzoyl group to undergo an intramolecular replacement reaction with neighboring group participation and transfer resulting in a more stable conjugation system of the 1,2,4-oxadiazol ring. A possible mechanism, as well as structural analysis and bioactivity are described.

Absolute configuration of the unique 2,6-dideoxy-4-O-methyl-arabino-hexopyranose of the major phenolic glycolipid antigen from Mycobacterium kansasii

The antigenicity and the structure of the major phenolic glycolipid from Mycobacterium kansasii have been established. A monoacetylated tetrasaccharide structure was proposed for the oligosaccharide moiety in which the distal sugar, unique in nature, corresponds to 2,6-dideoxy-4-O-methyl-alpha-arabinohexopyranose. Its terminal position in the oligosaccharide part confers to this residue a key role in the antigen-antibody interaction. By improvement of the methanolysis procedure, this new kind of sugar was obtained in higher amounts than by hydrolysis of the glycolipid. Its 1H-NMR spectrum is presented and its optical rotatory power measurement agrees with a D absolute configuration while the deoxyhexoses involved in the glycolipid tetrasaccharide structure present the L absolute configuration.

Two syntheses of 3-amino-3-deoxy-alpha-D-altropyranosyl 3-amino-3-deoxy-alpha-D-altropyranoside, a new analog of alpha,alpha-trehalose, involving reduction of a diazide and reductive amination of a diketone

A new diamino sugar, 3-amino-3-deoxy-alpha-D-altropyranosyl 3-amino-3-deoxy-alpha-D-altropyranoside (5) was synthesized by two routes starting from alpha,alpha-trehalose. The first route involved reduction and deprotection of a previously described, benzylidenated diazido analog. The second approach proceeded from the known 2,2'-di-O-benzyl-4,6;4',6'-bis-O-benzylidene derivative of alpha-D-altropyranosyl alpha-D-altropyranoside, to the corresponding 3,3'-diketone, which was subjected to reductive amination with sodium cyanoborohydride and ammonium acetate. The major product, separated in 39% yield from by-products after N-acetylation, was deprotected to give 5. Four by-products were isolated in low yields and determined to be monoaminated analogs which comprise two epimeric, 3'-hydroxy structures and two 3'-epimeric, 3'-cyano-3'-hydroxy structures in their non-aminated residues. A number of observations concerning the 13C- and 1H-n.m.r. spectra of the products are discussed, especially with regard to chemical-shift dependencies for certain ring and substituent protons, and attention is drawn to some inter-residue shielding phenomena.