D-Talose

D-Allose D-Altrose D-Glucose -Mannose D-Gulose D-ldose -Galactose D-Talose... 

Look up the structure of D-talose in Figure 25.3, and draw the fi anomer in its pyranose form. Identify the ring substituents as axial or equatorial. 

What other d aldohexose gives the same alditol as D-talose ... 

Die Reduktion der y-Lactone von On-sauren verschiedener Monosaccharide zu den entsprechenden Monosacchariden wird in einer geteilten Zelle an einer Quecksilber-Kathode undBlei- bzw. Platin-Anode in schwach saurem, waBrigen Milieu (Borat-Puffer) ausgefiihrt. Auf diese Weise sind d-Arabinose, n-Mannose, d-Talose, d-Ribose u. a. mit guter Ausbeute zuganglich1-4. 

Mannit 745 D- I-,4C- 224 3,4-Desoxy-D- 1,2 5,6-Bis-0-[isopropyliden]-3,4-dimercapto- 342 I,2 5,6-Bis-0-[isopropyliden]-3,4-trithiocar-bonato- 342 Sorburonsiiure l- -Calcium-Salz 317 T D-Talose 602... 

It has also been reported that D-galactose can be isomerized with molybdic acid to a mixture containing D-talose and D-gulose, but the yields are low.34-35 A number of derivatives of gulono-1,4-lactone have been prepared that, by reduction, would provide selectively protected derivatives of gulose. These derivatives will be discussed in subsequent Sections of this article. 

In addition to these physical studies at the Bureau, Tipson was able to return to his synthetic interests, both alone and in collaboration with other staff members. He was especially pleased to prepare D-talose in crystalline form, an accomplishment that had eluded Emil Fischer. Pursuing his longstanding interest in the reaction of sulfonic esters with iodide and following an earlier observation that the tetratosyl ester of erythritol is converted into butadiene by the action of sodium iodide and zinc, he demonstrated (with A. Cohen) that nonterminal unsaturation may be conveniently introduced into alditol derivatives by reaction of contiguous secondary sulfonates with sodium iodide and zinc dust in boiling A.A-dimethylformamide. This Tipson-Cohen reaction subsequently proved of great utility in other hands for the conversion of more complex carbohydrate structures into vicinal dideoxy derivatives. 

Hodosi, G. Kovac, P., Manipulation of free carbohydrates via stannylene acetals. Preparation of beta-per-O-acyl derivatives of D-mannose, L-rhamnose, 6-0-trityl-D-talose, andD-lyxose. Carbohydr. Res. 1997,303, 239-243. 

Methanol fiihrt weder zu dem erwarteten 2-Fluor-2-desoxy-Derivat, noch zu dem moglichen 2-0-Methylather. Unter Ringumlagerung entstehen hierbei die beiden Methylglykoside der 2,6-Anhydro-3,4-0-isopropyliden-D-talose 110,139) ... 

Die Desaminierung von Aminozuckern fiihrt in manchen Fallen zu ver-schiedenen Anhydro-Derivaten. Im Falle der 4-Amino-4-desoxy-l,6-anhydro-fl-D-mannopyranose wurde unter Waldenscher Umkehr am C-4 die l,6-3,4-Dianhydro-j3-D-talose erhalten is.nv). 

D-Talitol has been prepared by the reduction of D-talonolactone or D-talose. Recently, an improved method of preparation, the hydrogenation of D-altrose in high yield, has been described. ... 

Williams and J. K. N. Jones have shown that the dithioacetals of aldopentoses and aldohexoses may be separated as their acetates.472 In certain cases, however, isomers were not separated (for example, D-altrose and D-talose), but reduction of the dithioacetal to the 1-de-oxyalditol permitted resolution of the acetates. The method is not suitable for quantitative determinations, but it does preserve the... 

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