Monosaccharides heptoses

Monosaccharides are those carbohydrates that cannot be hydrolyzed into simpler carbohydrates They may be classified as trioses, tetroses, pentoses, hex-oses, or heptoses, depending upon the number of carbon atoms and as aldoses or ketoses depending upon whether they have an aldehyde or ketone group. Examples are listed in Table 13-1. 

Monosaccharides with four, five, six, and seven carbon atoms in their backbones are called, respectively, tetroses, pentoses, hexoses, and heptoses. There are aldoses and ketoses of each of these chain lengths ... 

L. Hough and A. C. Richardson, The monosaccharides Pentoses, hexoses, heptoses and highei sugars, in Rodd s Chemistry of Carbon Compounds, Vol. IF, G. Coffey, ed., Elsevier, Amsterdam, 1967, pp. 448-566. 

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... 

By means of the cyanohydrin reaction, higher sugars of the heptose. octosc, and nonosc types have been prepared. A monosaccharide such as an aldohexosc may be converted into the next lower monosaccharide, such as an aldopeniosc. by oxidation to the acid, which corresponds to the aldohexose. then treating the calcium salt solution of this acid with a solution or ferrous acetate plus hydrogen peroxide. Carbon dioxide is evolved and aldopentose formed. 

The simple sugars, or monosaccharides, are the building blocks of carbohydrate chemistry. They are polyhydroxy aldehydes or ketones with five, six, seven, or eight carbon atoms that are classified appropriately as pentoses, hexoses, heptoses, or octoses, respectively. They can be designated by more... 

A non-specific bacterial acid phosphatase from Shigella flexneri (PhoN-Sf) has been screened for regioselective phosphorylation of primary alcohol(s) of more than 20 different cyclic and acyclic monosaccharides using pyrophosphate as the phosphate donor (O Scheme 61) [368]. These studies have shown that PhoN-Sf is capable of phosphorylating a range of hexoses (D-glucose epimers, glycosides, and C-2 derivatives), pentoses, heptoses, ketoses, and acyclic carbohydrates. 

L-Arcanose and L-olimycose have been prepared in enantiomerically pure forms and with high stereoselectivity by Lewis-acid promoted addition of (5)-2-benzyloxypropanal to 1-tri-methylsilyl-2,3-butadiene. Depending on the nature of the Lewis acid either the syn (with TiCl4) or the anti adduct (with BF3 Et20) can be obtained. Epoxidation with lateral control by the allylic alcohol moieties and standard reactions lead to the unprotected monosaccharides [334]. Total syntheses of 2,3-dideoxy-3-C-methyl-D-maw o-heptose and of 2,3-dideoxy-2,3-di-C-methyl-D-gfycero-D-ga(acto-heptose have been realized by addition of 2-(trimethylsiloxy)furan to 2,3-0-isopropylidene-D-glyceraldehyde ((R)-37) [335]. 

Despite the fact that many heptoses are by far less prominent in Nature than hexoses these monosaccharides are found both as metabolic intermediates, and as structural carbohydrates of bacterial cell walls.D-Sedoheptulose 7-phosphate is an important intermediate of the pentose cycle, and D-sedoheptulose 1,7-bisphosphate is present in plants as an intermediate of the dark phase of photosynthetic reactions. L-Glycero-D-manno-heptose was isolated from the oligosaccharides obtained by partial acid hydrolysis of the lipopolysaccharide from Escherichia coli K-12 strain W3100 [153] and Haemophilus influenzae [154]. Both L-glycero-D-wtanno-heptose and D-glycero-D-ma o-heptose were isolated from the lipopolysaccharide of Vibrio parahaemolyticus [155]. 

Monosaccharides are identified by their carbonyl functional group (aldehyde or ketone) and by the number of carbon atoms they contain. The simplest monosaccharides are the two trioses glyceraldehyde (an aldotriose) and dihydroxyacetone (aketotriose). Four-, five-, six-, and seven-carbon-containing monosaccharides are called tet-roses, pentoses, hexoses, and heptoses, respectively. Structures of some monosaccharides are shown in Figure 9-1. All monosaccharides, with the exception of dihydroxyacetone, contain at least one asymmetrical or chiral carbon atom, and therefore two or more stereoisomers are... 

Monosaccharides may be called trioses, tetroses, pentoses, hexoses, heptoses, or octoses, depending on whether they have 3, 4, 5, 6, 7, or 8 carbons, respectively, in them. 

A monosaccharide can be a polyhydroxy aldehyde such as D-glucose or a polyhydroxy ketone such as o-liructose. Polyhydroxy aldehydes are called aldoses ( aid is for aldehyde ose is the suffix for a sugar), whereas polyhydroxy ketones are called ketoses. Monosaccharides are also classified according to the number of carbons they contain Monosaccharides with three carbons are trioses, those with four carbons are tetroses, those with five carbons are pentoses, and those with six and seven carbons are hexoses and heptoses, respectively. A six-carbon polyhydroxy aldehyde such as o-glucose is an aldo-hexose, whereas a six-carbon polyhydroxy ketone such as o-fructose is a ketohexose. 

---