Stereoselective synthesis of variably protected α- and β-l-Ara4N glycosyl H-phosphonates as key intermediates in the syntheses of β-l-Ara4N-modified LPS structures and α-l-Ara4N-containing biosynthetic precursors is reported. A facile one-pot approach toward β-l-Ara4N glycosyl H-phosphonates includes anomeric deallylation of protected 4-azido β-l-Ara4N via terminal olefin isomerization followed...

significant role in the rejection of the pathogen,i'2) Avenalumins consist of 3 components; the chemical structure ef the major component, avenalumin t, has been established to be 2-[2-(4hydroxyphenyl)ethenyl]-6-4H-3,1-benzoxazin-4-onc (1), based on an MS analysis of its acetylated derivative and identification of the methanolysis products.3) However, chem{cal studies by Crombie and Mistry4) ha...

When the water-soluble phosphate esters produced by mild alkaline methanolysis of rat brain lipids were separated on an anion exchange column, a fraction was observed which chromatographed between bis(glycerophosphoryl)glycerol and glycerophosphorylinositol phosphate. This compound did not correspond with the deacylation product from any phospholipid previously reported in brain. Evidence is pr...

A new polyfluorinated anti-staining coating material CF3O(CF2CF2O)xCF2-CONHCH2CH2CH2Si(OCH3)3 has been developed by utilizing the PERFECT method, which employs a liquid-phase direct fluorination reaction with elemental fluorine as a key step. Direct fluorination of a partially-fluorinated ester, which was prepared from a non-fluorinated poly(ethylene glycol) and a perfluorinated acyl fluoride, ...

Methyl 2,3,6-trideoxy-3-hydroxyamino-3-C-methyl-alpha-D-ribo-hexopyranoside+ ++ (2) and the corresponding amino sugar (4) were isolated from reduced viriplanin A by acidic methanolysis and esterified to the di-p-bromobenzoates (3 and 5), respectively. The absolute configuration of crystalline 3 was determined by X-ray analysis to be alpha-D. This result could be confirmed by oxidation of 2 to m...

Sulfobacins A and B are novel von Willebrand factor (vWF) receptor antagonists produced by Chryseobacterium sp. NR 2993. The structures of sulfobacins A and B have been determined to be (2R,3R)-3-hydroxy-2-[(R)-3-hydroxy-15-methylhexadecanamido]-15- methylhexadecanesulfonic acid and (2R,3R)-3-hydroxy-15-methyl-2-[13-methyltetradecanamido]- hexadecanesulfonic acid, respectively, by various 2D NM...

Inspired by biology, in which a bimetallic hydroxide-bridged zinc(II)-containing enzyme is utilized to catalytically hydrolyze phosphate ester bonds, the utility of a zirconium(IV)-cluster-containing metal-organic framework as a catalyst for the methanolysis and hydrolysis of phosphate-based nerve agent simulants was examined. The combination of the strong Lewis-acidic Zr(IV) and bridging hydro...

An enzyme extract from the phycocyanin-containing unicellular rhodophyte, Cyanidium caldarium, reductively transforms biliverdin IX alpha to phycocyanobilin, the chromophore of phycocyanin, in the presence of NADPH. Unpurified cell extract forms both 3(E)-phycocyanobilin, which is identical to the major pigment that is released from phycocyanin by methanolysis, and 3(Z)-phycocyanobilin, which i...

Introduction Structural determination of carbohydrates presents additional problems to those encountered in studies of linear biopolymers because of the multiple points of attachment between the constituent monosaccharide units and the resulting tendency of carbohydrate chains to branch. Further problems arise from the isobaric nature of many of the constituent monosaccharides and their ability...