Heptose manno

In a similar fashion it should be a relatively simple task to relate the well-known D-gala-L-manno-heptose (XX) to a-rhamnohexose (XXII)81 through the known 1-desoxy-D-gala-L-mcmno-heptitol (syn., 7-desoxy-L-manno-L- aZa-heptitol) (XXI).81 In. this particular case, however, there is already ample proof of the configuration of the latter sugar (XXII) because nitric acid has been found to oxidize the corresponding aldonic acid to mucic acid.82... 

D-Manno-D- olo-heptose diethyl thioacetal to l-desoxy-D-manno-D-jaZa- ... 

Heath and Ghalamboi29 31 had obtained a 2-deoxyheptose of unknown configuration by degradation with ceric sulfate of 15 (see Scheme 8), the product obtained upon reduction of KDO with sodium borohydride. Perry and Adams94 had shown this 2-deoxyheptose to be identical with 2-deoxy-D-manno-heptose (62 see Scheme 18), synthesized by Perry.91... 

Fig. 1. Higher-order sugars L-g/yceroD-manno-Heptose (1, open-chain and 2, a-pyranose) and A -acetylneurami ilic acid (3, a-pyranose form). Structures 4-8 depict D-glucose (4) as its open-chain Fischer projection, and as the a-oxetose (5), a-furanose (6), a-pyranose (7), and a-septanose (8) ring forms.

D-Manno- D-galsi-heptose. Hexaacetyl-D-manno-D-goZa-heptononitrile was prepared by Miksic and by Brigl, Miihlschlegel and Schinle by acetylation of the free nitrile. It was degraded with methanolic ammonia and silver nitrate, giving D-mannose diacetamide in 34% yield. 

L-gij/cero-D-manno-Heptose Ucon 50LB-550X NPGS 5% Ucon LB-550 192... 

Scheme 1) whereas the reaction with the D-man/io-hexodialdo-l,5-pyranose derivative 3 produced, in low yield, the cyanohydrin 4 having an L-glycero-D-manno configuration and the stereoisomeric epimer at C-5, rather than at C-6 [14J. With an atm toward the synthesis of d- and L-glycero-D-manno-heptoses, the reaction of 3 with other reagents (2-inethyl-furan, alkyl magnesium chlorides) was also explored, without any substantial improvement of either stereoselectivity or yield. 

Although the reaction of sodium cyanide with 2,6-anhydro-o-glycero-L-manno-heptose (6) (Scheme 2), a C-formyl galactopyranoside, seemed to occur with high level of... 

M. Dasser, F. Chretien, and Y. Chapleur, A facile and stereospecific synthesis of L-glycero-D-manno-heptose and some derivatives, J. Chem. Soc. Perkin Trans. 7 3091 (1990). 

Circles represent polar head groups of phospholipids. MDO, membrane-derived oligosaccharides KDO, 3-deoxy-manno-octulosonic acid (structures for KDO and heptose are in Fig. 4-15). From Raetz and Dowhan.587... 

In a similar fashion, KDO is converted to the P-linked CMP-KDO,56 56b which is incorporated into lipid A as shown in Fig. 20-10. The ADP derivative of the i -glycero-o-manno-heptose (Fig. 4-15), which is also present in the lipopolysaccharide of gramnegative bacteria, is formed from sedoheptulose 7-P in a five-step process (Eq. 20-9).57 58b... 

In this group of monosaccharide components of bacterial polysaccharides, a primary glycosyl nucleotide is ADP-D-g/ycero-D-manno-heptose (9), identified in extracts of a mutant strain of Shigella sonnei.231... 

Formation of a possible precursor of 9, namely, o-glycero-D-manno-heptose 7-phosphate, from D-sedoheptulose 7-phosphate was demonstrated in Salmonella typhimurium.238... 

Biosynthesis of the most common constituent of the bacterial-lipopolysac-charide core, L-glycero-D-manno-heptose, was shown239,240 to occur through enzymic epimerization at C-6 of the heptosyl group in 9. Genetic evidence241,242 supports this pathway of biosynthesis. 

B) Heptoses and heptuloses D-Sedo(altro)heptulose 30, D-manno-heptulose 33, D-glycero-D-guloheptose 8, D-glucoheptulose 20, L-gluco-heptulose 8, L-galactoheptulose 40. 

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