Tetrose 4-deoxy-2-

The 3-deoxy pentose phosphates (44 and 45) can be further degraded to phosphorylated deoxy sugars (58) treatment of either of them with periodate will cleave the carbon-carbon bond between Ci and C2 to yield 2-deoxy-n- (46) and -L-gZycero-tetrose-4-phosphates (47). 

In connection with the Webb and Levy test, it should be mentioned that this test can also be applied to the estimation of all 2-deoxy aldoses, including those containing a terminal deoxy group, provided they have at least five carbon atoms in a straight chain 2-deoxy tetroses do not react (62). It has also been used for the estimation of 3-deoxy and 3, 6-di-deoxy hexoses, after their conversion to the corresponding 2-deoxy pentoses by removal of carbon 1 with periodate (24,25). 

I, 7-diphosphate.170 1 (f> This tetrose phosphate is involved with phosphoenol pyruvate in the formation of shikimic acid via 3-deoxy-2-keto-D-ara6ino-heptonic acid 7-phosphate and, hence, of aromatic compounds.170(d) A synthesis of the tetrose phosphate has been described.170 1 Aldolase shows a high affinity for the heptulose diphosphate and, compared with that for D-fructose 1,6-diphosphate, the rate of reaction is about 60 %. The enzyme transaldolase, purified 400-fold from yeast, catalyzes the following reversible reaction by transfer of the dihydroxyacetonyl group.l70(o>... 

Deoxy-3-(hydroxymethyl) -d -glyc-ero-tetrose (cordycepose) H H HOHj C—C—C—CHO HO HOH2C metabolic product of Cordyceps mililaris Link47 ... 

Deoxy-2-(2-hydroxyethyl)tetrose CHO lipopolysaccharide from Salmonella... 

Table 1. Comparison of Optimized Molecular Parameters For the Planar Conformer of 2-Deoxy-a-D-giycero-tetrose 7 Obtained With Different Basis Sets...

Some of the alditol acetates formed from deoxy sugars, pentoses, and tetroses are particularly volatile, and care should be taken when evaporating to dryness (see Basic Protocol 1, step 21). It is best to stop the evaporation as soon as the sample is dry. 

The aldehyde l-149 reacts with diallylzinc to give 158 as the major product, the ozonolysis of which, when followed by acidic hydrolysis, furnishes 2-deoxy-L-fucose, which is a component of several antibiotics [103]. Similarly, 159 can be converted into L-mycarose (2,6-dideoxy-3-C-methyl-L-n7 (9-hexopyranose). The same anti preference is observed for all these diallylzinc additions (Scheme 13.56). Using allylmagnesium bromide leads to mixtures of anti and syn adducts. The syn adducts derived from l-149 and 159 were converted as above into 2,6-dideoxy-L-araZpmo-hexopyranose 160 and into L-boivinose 161, respectively. For other examples of tetrose derivative allylations, see Ref. [104]. 

Finally, the mutarotation of tetra-O-acetyl-n-arohfno-hexose phenylosa-zone, of 4-deoxy-L-ffZyccro-tetrose phenylosazone, and of tetra-O-acetyl-D-lyxo-hexose phenylosazone can in no way be explained by cyclization, since in these cases there is definitely no possibility for ring formation to take place. 

The simple and well-established behavior of alditol acetates upon electron impact makes these derivatives suitable for identification of sugars. Thus, tetroses, pentoses, hexoses, and heptoses give characteristic spectra that can be fully interpreted. The presence and positions of deoxy groups or acetamido functions can readily be determined. Ambiguities... 

Nagakawa and co-workers investigated the use of simple acetylenic alcohols for the synthesis of trioses, tetroses, and l-deoxy-eo f/t/ o-pentose. 

Monosaccharides. M. are linear polyhydroxyalde-hydes (aldoses) or polyhydroxyketones (ketoses). Most important among M. are the pentoses (CjHiqO,) and hexoses (C6H,20 ). Important aldopentoses include, e.g., D- ribose, D- xylose, and L- arabinose. Important aldohexoses include D- glucose, D- man-nose, and D- galactose the major ketohexoses are D- fructose and sorbose. The 6- deoxy sugars L- fu-cose and L- L-rhamnose are also widely distributed hexoses. M. with more carbon atoms (heptoses 7 carbon atoms, octoses, etc.) or less carbon atoms (trioses 3 carbon atoms) do not occur in the free form in organisms but do play a role in carbohydrate metabolism as phosphate esters tetroses (4 carbon atoms) erythrose, threose are relatively rate. 

Tetroses and Pentoses - 4-0- -Butyldimethylsilyl-2,3-0-isopropylidene-L-threose (1) has been prepared in seven efficient steps from o-xylose. 3,4-0-Isopropylidene-D-eythrulose (4) has been synthesized from the known tetritol derivative 2 by primary protection as the silyl ether 3, followed by Dess-Martin oxidation and desilylation. Compound 2 was derived from D-isoascorbic acid (see Vol. 22, p. 178, refs. 9,10). In a similar reaction sequence, the enantiomer 5 has been obtained from L-ascorbic acid. The dehomologation of several di-0-isopropylidenehexofuranoses e.g., 6- 7) has been carried out in two steps without intermediate purification, by successive treatment with periodic acid in ethyl acetate, followed by sodium borohydride in ethanol. Selective reduction of 3-deoxy-D-g/jcero-pentos-2-ulose (8) to 3-deoxy-D-g/> cero-pent-2-ose (9) has been achieved enzymically with aldose reductase and NADPH." 4-Isopropyl-2-oxazolin-5-one (10) is a masked formaldehyde equivalent that is easily converted to an anion and demasked by mild acid hydrolysis. One of the three examples of its use in the synthesis of monosaccharides is shown in Scheme 1. ... 

Aldol condensation of 2,2-diethyl-l,3-dioxolan-4-one lithium or zirconium enolates with aldehydo sugars has afforded higher carbon aldonic acid derivatives, e.g. 1. The synthesis of L-ribono-1,4-lactone has been achieved from d-isoascorbic acid by way of the tetrose and pentitol derivatives 2 and 3 and the d-ribonolactone derivative 4 has been efficiently epimerized to the L-lyxonolactone 5 (Scheme 1). A selective i yn-epoxidation of racemic 2-0-benzyl-4-alkenamides followed by hydrolysis has afforded 3-deoxy-pentono-1,4-lactones. 

The use of ( )-malic acid as a source of 2-deoxy-D-erythro-tetrose and hence 1,2-anhydro-3-deoxypentitols en route to milbemycin is mentioned in Chapter 24. 

Monosaccharides are polyhydroxy aldehydes (aldoses) or polyhydroxy ketones (ketoses). They are classified as trioses, tetroses, pentoses, hexoses, etc. according to the number of carbon atoms. With the exception of dihydroxy acetone, monosaccharides contain one or more chiral C-atoms. Most monosaccharides carry an oxygen-containing group at each carbon atom. However, there are also deoxy sugars which have one or several oxygen-free carbon atoms. 

Azido-sugars are frequently prepared by reaction of epoxides with azide ion. 3-Azido-3-deoxy-L-threose 68 was synthesized from cu-but-2-ene-l,4-diol 66 via the Sharpless asymmetic epoxidation product 67, and was converted into 6-azido-6-deoxy-L-galocro-heptulose 69 by an enzyme-catalyzed aldol condensation (Scheme 13). 3-Azido-3-deoxy-L-etythrose, and thence 6-azido-6-deoxy-L-g/uco-heptulose were obtained in a similar way via 4-rerf-butyldiphenylsilyoxy-rraiu-but-2-enal. These and two other azido-heptulose isomers made from the enantiomeric 3-azido-3-deoxy-tetroses, were converted to a- and P-l-homonojirimycin and homomannonojirimycin on hydrogenation. Ethyl 3-azido-2,3-dideoxy-D-eryr/iro-pentopyranoside and its 3-C-methyl analogue 71, R=H or Me, were synthesized from crotonaldehyde or 3-methyl-2-... 

The parent trioses, tetroses, pentoses and hexoses which are fimdamental to carbohydrate stereochemical nomenclature are shown. Derivatives of these, such as deoxy-, aminodeoxy- etc. derivatives are not included. 

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