Similar Sugars

Nomenclature or Higher-carbon Sugars from Hexoses 

The reader will note that in the older literature rhamnose and fucose are classified as methylpentoses preference is now given to their designation as desoxy-hexoses. The old name rhamnoheptose has thus become L-rhamnooctose and rhamnooctonic has become L-rhamno-nononic. 

Its preponderance in the synthesis, high dextrorotation ([a]n +50°, equilibrium) and the low solubility of the phenylhydrazide of its aldonic acid are good signs that it resembles D-galactose rather than D-talose. 

Edna M. Montgomery, N. K. Richtmyer and C. S. Hudson, J. Am. Chem. Soc., 65, 1852, note 17 (1943), data from work by Olive P. Hartley T. Mueller and T. Reichstein, Hdv. Chim. Acta, 21, 253 (1938). 

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ChSS and DASS were rich in arabinose, galactose and uronic acids. These were, as expected, pectin-rich extracts and had a very similar sugar composition. The 1 MASS fraction was also rich in arabinose, galactose and uronic acids, but next to that it is also enriched in... 

Similarly sugar-SNAPs (Fig. 8.3) developed by Wang and his group [27-30] have interesting pharmocokinetic properties. 

Chemical properties, configuration and, of similar sugars, I, 26 Chemisorption, between enzyme and substrate, V, 56... 

We can also easily convert hydroxyl groups to silyl ethers. Section 14-10B covered the use of the triisopropylsilyl (TIPS) protecting group for alcohols. Similarly, sugars can be converted to their silyl ethers by treatment with a silyl chloride, such as chlorotrimethylsilane (TMSC1), and a tertiary amine, such as triethylamine. 

Nucleotides can contain either of two similar sugars. RNA nucleotides contain a five-carbon sugar called ribose, whereas DNA nucleotides contain deoxyribose, which has the same general structure as ribose but with a single hydrogen atom in place of one of the hydroxyl groups. 

The yeasts exhibited a similar sugar utilization pattern (data not shown). Glucose and xylose were assimilated simultaneously, the former at a higher rate, enabling higher growth rates. Xylose was completely assimilated by P. stipitis and D. hansenii, but not by K. marxianus, which only consumed 70%. Arabinose was also assimilated by all yeasts simultaneously with late xylose assimilation, being only completely exhausted by D. hansenii. The other two yeasts, Pichia stipitis and K. marxianus, only consumed 31 and 45% of available arabinose, respectively. Furfural, acetic, and formic acid were also consumed (data not shown). 

Interestingly, several cyclic sulfates react with telluride ion generated in situ by reduction of elemental tellurium to yield alkene under mild conditions (0°C) [Eq. (23)]. For example, 4,5-diphenyl-l,3,2-dioxathiolane 2,2-dioxide gave irum-stilbene. Similarly, sugar derivatives can be converted into an unsaturated sugar (95TL7209) [Eq. (24)]. 

Similarly, sugar-linked iodolactones (72), prepared by a four-carbon elongation-idol-actonization route, were converted into sugar-linked butenolides (100a and 100b). i The butenolides thus made successfully underwent INC reaction to give bicyclic isoxazolidine saccharides (101a and lOlb) (Scheme 22.23). 

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