Pyranose

About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.

A straightforward synthesis of DAH (3-deoxy-D-arabino-hept-2-ulosonic acid) and DRH (3-deoxy-D-ribo-hept-2-ulosonic acid)

Abstract: Based on the oxidation of corresponding terminal alkynes to α-keto esters, DAH (3-deoxy-D-arabino-hept-2-ulosonic acid) in its pyranose form and DRH (3-deoxy-D-ribo-hept-2-ulosonic acid) in its protected pyranose–furanose mixture form were efficiently synthesized. These terminal alkynes were in turn obtained by C1- or C3-homologation of corresponding protected sugars, respectively. Along with the application of this strategy, the syntheses of two C6-ulosonic acids, 3-deoxy-D-erythro-hex-2-ulosonic acid and 3-deoxy-L-erythro-hex-2-ulosonic acid in their protected pyranose form, were also described.

1,2‐propanediol–cellulose–acrylamide graft copolymers

Abstract: 1,2-Propanediol–cellulose–acrylamide graft copolymers (PCACs) were developed for enhanced oil recovery. They were prepared with acrylamide and 1,2-propanediol (PDO)–cellulose, which was formed through the addition of glycols to cellulose by the Shotten–Baumann reaction between 3-chloro-1,2-propanediol and cellulose. The graft copolymerization was initiated with a redox system between Ce4+ and glycols in cellulose. The infrared spectrum of PDO–cellulose had some characteristic absorption bands around 2960 (νCH) and 1050 cm−1 (νCO) that also appeared for the PDO group and pyranose ring of cellulose, respectively. The rate of Ce4+ consumption by PDO–cellulose was investigated through the calculation of the overall kinetic constant from the slopes of ln(D − DR) versus time (where D is the absorbance and DR is the absorbance of the original polysaccharide solution) The results showed that PDO–cellulose had high reactivity and that there were two mechanisms of oxidation by Ce4+ with PDO–cellulose. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3022–3029, 2004

Identification of Stereoisomers of Methyl Hexopyranosides by Mass Spectrometry of Their Trifluoroacetates

Abstract: The mass spectra of the trifluoroacetates of methyl hexopyranosides and their partially deuterated derivatives were measured. The trifluoroacetyl derivatives were found to be very useful for identification of some stereoisomeric hexoses. The mass spectra were characterized by abundant peaks in the high mass range, the presence of a recognizable molecular ion, and sensitive spectral differences due to different stereoisomers. Glucose, galactose and mannose were distinguished from each other by comparing the intensities of the fragment ions due to the loss of trifluoroacetyl groups or cleavage of the pyranose ring. Alfa and β-anomers were distinguished by differences in the abundance of fragment ions produced by the loss of glycosidic methoxyl groups.

Synthesis of 13C‐enriched pyrrole from 2‐13C d‐galactose

Abstract: The synthesis of 13C-enriched pyrrole, labeled adjacent to the nitrogen atom, is described. A convenient and effective bench-top synthesis is given which uses a readily available enriched pyranose sugar, 2-13C d-galactose, as the starting material. In the first step of the synthesis, d-galactose is oxidized to produce mucic acid in 70–75% yield. Mucic acid is then treated with ammonium hydroxide to give ammonium mucate in 99% yield. In the final step, ammonium mucate is pyrolyzed to form pyrrole with a 35% yield. The pyrrole obtained in this manner is greater than 98% enriched at the α position. Copyright © 1999 John Wiley & Sons, Ltd.

Chemistry of carbohydrate aziridines.

Abstract: Publisher Summary This chapter discusses the chemistry of carbohydrate aziridines, with emphasis being placed on surveying preparative methods and ring-opening reactions. Carbohydrate aziridines or epimines are derivatives in which an aziridine ring is fused to a pyranose or furanose ring or to an exocyclic part of a carbohydrate molecule. From the mechanistic point of view, the reported syntheses of carbohydrate aziridines are based almost exclusively on S N 2 intramolecular nucleophilic substitution. The nucleophile is a nitrogen-containing group, often free or an N -substituted amino group, which can be generated in situ by the reduction of an azido or cyano group, or by the Michael addition of amines to a double bond with appropriate substitution. The neighboring leaving group is typically an alkyl (aryl)sulfonyloxy group, or is generated in situ , which is the case with the Mitsunobu reaction. The aziridine-ring closure invariably proceeds with the inversion of configuration at the atom bearing the leaving group. The stereochemistry of S N 2 nucleophilic substitution strongly favors the antiperiplanar disposition of the participating groups in the transition state. This chapter describes the methods for the synthesis of carbohydrate aziridines. It also explains the general properties of carbohydrate aziridines and elaborates the reactions of carbohydrate aziridines.