Diuloses

The D-fructose-derived ketone (25) reacts with Grignard reagents 

6-bisphosphate ( 5-keto-D-fructose esters) in water has shown that the former exists mainly in the 3-pyranose form (27) with the remainder in the 2R,5R-furanose form (28). The bisphosphate exists as the 2R,5R (29) ( a. 80 ) and the (2S,5R) isomers. 

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Oxidation of hydioxyl groups to carbonyl groups can form molecules with two aldehyde groups (dialdoses), two ketone groups (diuloses), or an aldehyde and a ketone group (osuloses). Keto acids are known as ulosonic acids. 

The systematic name of a diketose is formed by replacing the terminal -se of the stem name by -diulose . The locants of the (potential) carbonyl groups must be the lowest possible and appear before the ending. The stem name is preceded by the appropriate configurational prefix. If there is a choice of names, a decision is made on the basis of 2-Carb-2.2.2. In cyclic forms, locants may be needed for the positions of ring closure that of the (potential) carbonyl group is cited first. 

D-g/ycero-o-/cfo-Nono-3,6-diulose 2-Carb-12. Ketoaldoses (aldoketoses, aldosuloses)... 

Ditrimethylolpropane, 2 47 physical properties of, 2 48t Ditungsten boride, 25 386 Ditungsten trisilicide, 25 386 Diucardin, molecular formula and structure, 5 162t Diuloses, 4 711 Diuretics, 22 867 Diuril, 5 168... 

Both the alio and manno epoxides (9) or (7), or their debenzyliden-ated analogs, undergo oxidation with methyl sulfoxide and boron trifluoride,104 but, unlike 5,6-anhydrohexofuranose derivatives (see p. 163), they do not yield a simple a-hydroxy carbonyl compound, as would be expected by analogy with simple oxiranes instead, the rearranged diulose (46) is obtained in low yield, possibly by elimination of methanol from the intermediate (47). 

D-fhreo-2,5-Hexodiulosonic acid, having a keto group at both C-2 and C-5 is, like the corresponding diulose, preponderantly in the yS-pyranose form in solution, with the 5-keto group fully hydrated.100... 

A related reaction of more general applicability occurs with the octos-3,7-diulose derivative 27, which was made from the C-3 epimer of dialdose acetal 4 by treatment with (2-oxopropylidene)triphenylphosphorane in a Wittig chain extension reaction, followed by hydrogenation of the resulting enone and oxidation of the alcohol groups at C-3 and C-7. Cyclilzation to give the crystalline tertiary alcohol 28 in 81% yield is promoted by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing benzene (Scheme 7) [16]. 

A labile 4,6-dideoxy- /Z /cero-hexos-2,3-diulose (actinospectose) (60)288 2 8 has been isolated, as the crystalline bis-[(2,4-dinitrophenyl) hydrazone] of... 

In the context of the development of enzymatic methods for the synthesis of higher-carbon sugars we recently developed a new strategy by which dodeca-2,11-diuloses — formally derived from ketohexoses by C-coupling tail to tail — become accessible with deliberately addressable substitution patterns by the twofold aldolase-catalyzed chain elongation ( tandem aldolization) of simple, readily available dialdehydes [207]. The choice of furanoid (179) or pyranoid (180) nature of the products can be determined by a suitable placement of hydroxyl substituents in the allylic (181) or homoallylic ( 182) positions of a corresponding cycloolefinic precursor. 

A quinone-dependent sugar oxidoreductase, purified from Agaricus bisporus, catalyzes C-2 and C-3 oxidation of D-glucose to o-arabino-hexos-2-ulose and preferentially to D-n fto-hexos-3-ulosc. The two aldoketoses accumulate transiently in the reaction mixture, being converted into the same end-product, D-eryt/zro-hexos-2,3-diulose. D-Galactose is oxidized exclusively at C-2 to produce D - /y.w - h c x o s - 2 - u 1 o s c.447 Fukui and Hochster448 prepared n-/vAo-hexos-3-ulose (219) by enzymic oxidation and hydrolysis of sucrose. 

Diuloses and alduloses are the main products when aqueous solutions of sugars are gamma-irradiated in the presence of oxygen.481... 

Crude enzyme extracts from the white-rot fungus Oudemansiella mucida oxidize D-glucose to D-pryt/zro-hexos-2,3-diulose (265) via o-arabino-hexos-2-ulose. Compound 265 was identified by NMR and mass spectroscopy of the N, N- di p he n y 1 h y dr a zo ne derivatives 491... 

Oxidation of l,2 5,6-di-0-isopropylidene-o-mannitol (269) with dimethyl sulfoxide-acetic anhydride gave the 3,4-diulose derivative 270, which on hydrolysis led to crystalline 271. Some derivatives, such as 272 and 273 have been prepared.496... 

J. Vole, P. Sedmera, V. Havlicek, V. Prikrylova, and G. Daniel, Conversion of D-glucose to D-ertt/zro-hexos-2,3-diulose (2,3-diketo-D-glucose) by enzyme preparations from the basidiomycete Oudemansiella mucida, Carbohydr. Res., 278 (1995) 59-70. 

M. A. Glomb and C. Pfahler, Synthesis of l-deoxy-D-ertt/zro-hexo-2,3-diulose, a major hexose Maillard intermediate, Carbohydr. Res., 329 (2000) 515-523 and references cited therein. 

Uloses are derivatives of carbohydrates, which contain a further keto group. Aldosuloses are obtained from aldoses and diuloses from ketoses. They are important intermediates in the synthesis of carbohydrates. Uloses can be prepared by oxidation of derivatives in which all the hydroxyls except that one subjected to oxidation are blocked. Uloses are formed as intermediates during pulp bleaching (see Section 8.1.3). 

L- /ireo-Hex-2,3-diulosic acid y-lactone (L-dehydroascorbic acid)... 

The only reported acyclo C-nucIeoside of this kind 75 was prepared by Hanisch and Henseke upon heating the l,5 4,6-dianhydro-2,3-hexo-diulose bis(phenylhydrazone) 74 with copper(II) sulfate (68CB4170) (Scheme 23). 

The original purpose was to cyclize this compound to a cyclitol derivative by treatment with potassium in xylene. However, a crystalline diene derivative (115) was formed which, after hydrolysis of the methylene groups, gave crystalline l,6-dideoxy-D-(/ireo-2,5-hexodiulose (116). It showed no indications of the presence of a double bond and reduced Fehling solution in the cold. The location of the two keto groups at C-2 and C-5 in this compound and in the diulose (118), obtained later, was proved by ozonization of their parent diene compound (115) to yield D-threaric acid. The compound (116) showed no mutarotation and was converted into a crystalline bis[(p-nitrophenyl)hydrazone] and di-(p-nitrobenzoate). 

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