Beta anomers

Diels-Alder reaction of, 575 electrostatic potential map of, 576 evidence for, 575 structure of, 576 Bergman, Torbern, 2 Bergstrom, Sune K., 1068 Beta anomer, 984 Beta-carotene, structure of, 172 industrial synthesis of, 722 UV spectrum of, 504 Beta-diketone, 851... 

Figure 9.6 Anomeric forms of D-glucose and D-fructose. The alpha and beta anomers are named with reference to the configuration of the glycosidic hydroxy] group associated with the oxygen bridge.

Figure 9.17 Alpha and beta anomers of maltose. When only the hydroxyl group on the anomeric carbon of one of the monosaccharide residues is involved in the glyco-sidic linkage, the anomeric hydroxyl group on the other residue is still free. This permits two possible orientations, which are described as either alpha or beta forms of the monosaccharide residue.

The probable configuration of isosucrose was systematically discussed by Georg,who thought that the yield was much greater when the beta anomer, rather than the equilibrium mixture or the alpha anomer, of 2,3,4,6-tetraacetyl-D-glucose was used in the condensation. Analogy with tetraacetyl-D-fructopyranosyl chloride, which yielded the acetylated... 

When a monosaccharide forms a cyclic hemiacetal (or hemiketal), the carbonyl carbon becomes a stereocenter. Thus, cyclization leads to formation of two possible stereoisomers. These isomers are called anomers, and the former carbonyl carbon is called the anomeric carbon. The isomer with the anomeric OH (shown in blue) pointed down is the alpha anomer. The isomer with the anomeric OH (shown in blue) pointed up is the beta anomer. (Figure 12.14)... 

A five-membered cyclic sugar ring is called a furanose. Fructose prefers a fu-ranose ring system, and is formally named fructofuranose. Like glucose, fructose can cyclize and can form either an alpha anomer or a beta anomer. Notice that,... 

Anomerization can conceivably be brought about by dissociation of the Cl-to-ring-oxygen bond, followed by reclosure of the ring to form either the alpha or beta anomer.98... 

UDP-galactose and UDP-D-glucose in galactose metabolism also catalyzes the conversion of a-D-glucose or a-D-galactose to their beta-anomers... 

Another advantage of chromatography at elevated temperatures is that the rate of interconversion of the alpha and beta anomers of some saccharides may be increased, resulting in the eUmination of... 

Lee J, Park G-S, Yang WK, Kim JH, Park CH, An Y-H, Lee YJ, Chang Y-K, Lee GS (2009) Methods for preparing capecitabine and beta-anomer-rich trialkyl carbonate compound used therein. WO 2009066892... 

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