Of D-gulose

As discussed in Sect. 3.4, the synthon 20 was prepared from the dibromo-heptonolactone, which in turn was obtained from the cheap commercially available D-g/ycero-D-gu/o-heptono-l,4-lactone (Table 1). The other isomeric dibro-moheptonolactones shown in Table 1, which were prepared from the heptonates, obtained from chain extension of D-mannose and D-galactose, respectively, were also converted into unsaturated bromodeoxyheptonolactones. Finally, we obtained 2-0-acetyl-7-bromo-3,7-dideoxy-D-xyZo-hept-2-enono-l,4-lactone and the corresponding D-/yxo-isomer by the Kiliani extension of D-gulose. These substrates were all cyclized to cyclopentane lactones, stereoisomers of 65 [98]. 

Some 40 years ago Isbell (16) observed complex formation between calcium ions and a sugar which possesses the ax-eq-ax sequence—i.e., a-D-gulopyranose. He observed that an equilibrated solution of D-gulose, CaCl2, underwent further mutarotation on dilution with water and he correctly interpreted the phenomenon by postulating that a-D-gulo-pyranose (10), but not -D-gulopyranose, forms a complex with calcium... 

G. J. F. Chittenden, Oxidation of some derivatives of D-galactose with methyl sulphoxide-acid anhydride mixture a route to derivatives of D-gulose and D-talose, Carbohydr. Res., 15 (1970) 101-109. 

By treatment of D-gulose (XVII) or D-idose (XVIII) with warm aqueous barium hydroxide solution Van Ekenstein and Blanksma were able to isolate D-sorbose (II) with a melting point of 165° and [< ]d + 42.9° in water. The aldoses were prepared from D-gulonic and D-idonic lactones obtained by the cyanohydrin synthesis from D-xylose. 

How is the product from the reduction of D-glucose with NaBH4 related to that from reduction of D-gulose ... 

Related studies with 3-0-acetyl-l,2 5,6-di-0-isopropylidene-a-D-erythro-hex-3-enose (63, R = OAc), which can be prepared crystalline, and in good yield, from l,2 5,6-di-0-isopropylidene-a-D-rtbo-3-hex-ulose hydrate, have provided a useful new synthesis122 of D-gulose, because sodium borohydride causes efficient reduction to crystalline l,2 5,6-di-0-isopropylidene-a-D-guIose (64). Conversely, the unsaturated derivative (63, R = H) was produced, together with the 3-deoxy-3-fluoro-D-galactose compound on treatment of l,2 5,6-di-0-isopropyIidene-3-O-p-toIyIsulfonyl-D-gulose with tetrabutylammo-nium fluoride in acetonitrile.1223... 

Preparation. D-Gulose may be obtained as a pure syrup by the Kiliani synthesis from D-xylose.111 Crystalline a-D-gulose.CaCl2.H2O was obtained upon evaporating in vacuo an aqueous solution of D-gulose containing about two molecular equivalents of calcium chloride.112... 

This new aldohexose, if it were formed, would be an l sugar and it would be the mirror reflection of D-gulose. Thus its name would be L-gulose. 

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