Talose derivatives

The (—)-anisomycin work is presented in Scheme 35. Its key step centered around the formation of a pyrrolidine ring that possessed all three of the asymmetric centers present in the target this was done by nucleophilic displacement of a 3-tosyloxy function in an appropriately functionalized 6-amino-6-deoxy-p-i.-talose derivative, whose 1,2-diol was later released and oxidatively cleaved with sodium periodate. Grignard coupling, O-acetylation, and catalytic hydrogenation then furnished the desired natural-product target. 

Quite analogous ring-closures occur when the 1-O-acetyl derivatives of the rhamnopyranose and talopyranose derivatives are treated with sodium azide in N,N-dimethylformamide. l-O-Acetyl-6-deoxy-2,3-0-isopropylidene-4-0-mesyl-a-L-mannopyranose is converted exclusively into l,4-anhydro-6-deoxy-2,3-0-isopropylidene-/3-L-talo-pyranose. In this instance, the azide nucleophile attacks the l-O-ace-tyl group, liberating an 0-1 oxide ion which reacts with inversion of C-4. The 4-epimeric, l-O-acetyl-6-deoxy-talose derivative gives 60% of the direct inversion product l,4-anhydro-6-deoxy-2,3-0-isopropyli-dene-a-L-mannopyranose, together with other products.50... 

F]DGal, 119, a useful tracer to measure galactose metabolism in the liver with PET162b, has been synthesized by 18F ion displacement from a triflate163-165. The protected carbohydrate 120 has been oxidized163 and then reduced by LAH to give the talose derivative 121 which, in turn with triflic anhydride and pyridine, furnished the triflate intermediate 122. [18F]fluoride displacement on the latter and deprotection by acid hydrolysis yielded 119, in 30% r.y. in 90 minutes. 

A synthesis of D-evalose (6-deoxy-3-C-methyl-D-mannose) utilized an enolate methylatlon reaction for the conversion of the 4-ulose (8) to the 3-C-methyl analogue (9) LAH reduction of (9) led to the talose derivative (10), whereas NaBH reduction of the 2, 3-dl-O-acetyl analogue of (9) gave the required mannose derivative (11)... 

The 6-deoxy-L-talose derivative 14 was the major product of osmium mtroxide hydroxylation of the alkene 13, itself prepared from di-O-acetyl-L-rhamnal by allylic rearrangement followed by Mitsunobu inversion at C-4.U 6-Deoxy-D- ructose and 6-deoxy-L-sorbose were obtained as a separable mixture from the transketolase-catalysed reaction of hydroxypyruvate with 2,3-dihydroxybuQialdehyde (mixture of isomers) (Scheme 4). ... 

The 2,5-anhydro-L-idose 3,6-disulphonate ester derivative (9), prepared from D glucose in good yield, had been used to synthesize both Danhydro-talose derivative formed from (9) which with lithium aluminium... 

Mannopyranoside derivatives having poly-alkylated benzene attached via a C-l-acetamido group and the equivalent talose derivative were used as models to... 

The Action of Alkaline Reagents on 2 3-1 6- and 3 4-l 6-Dianhydro-3-talose. A Constitutional Synthesis of Chondrosamine and other Amino-Sugar Derivatives, S. P. James, F. Smith, M. Stacey, and L. F. Wiggins, J. Chem. Soc., (1946) 625-628. 

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. 

The legioselectivity of electrophilic additions of the C=C double bond in 7-oxabicyclo[2.2.1]hept-5-en-2-yl (7-oxanorbom-5-en-2-yl) derivatives depends on the nature of the substituents at C(2). The adducts so-obtained can be transformed into the corresponding 5,6-disubstituted 7-oxanorboman-2-ones, which can be mono-substituted at C(3) stereoselectively, giving products with the same stereochemical information as hexoses. Thus, optically pure 7-oxanorbom-5-en-2-yl derivatives can be viewed as "naked sugars" Applications to the total, asymmetric syntheses of L-daunosamine, 2-deoxy-L-fucose, D- and L-aUose, D- and L-talose, D- and L-ribose,... 

Total Synthesis of D- and L-AUose, D- and L-Talose and of D- and L-Ribose Derivatives... 

A. C. Richardson, Derivatives of 3-amino-3,6-dideoxy-L-glucose and -L-talose, Proc. Chem. Soc. (1961) 255. 

A. C. Richardson and K. A. McLauchlan, 3-Amino-3-deoxy-derivatives of L-glucose, L-galactose and L-talose,/. Chem. Soc. (1962) 2499-2506. 

As a consequence, 4,6-O-isopropylidene derivatives are obtained from D-aldohex-oses this has now been demonstrated not only for D-allose, D-galactose, D-glucose, D-mannose, and D-talose, but also for D-gulose (J. Gelas and D. Horton, unpublished results see also, Ref. 15) it may reasonably be assumed that it will also be found for D-altrose and D-idose. 

As the table shows, certain pairs of derivatives have the same melting points, although the underivatized monosaccharides do not. Why do glucose and mannose, and galactose and talose, form osazone derivatives with the same melting points ... 

The exo/endo (99 1) adducts are of 90-92% optical purity. The enantiomeric bicyclic ketones can be transformed into carbohydrates in a few, stereochemically well-defined steps. In this way, derivatives of d- and L-ribose [38], L-allose, L-talose, and such [39] have been obtained. 

The 2-0-(2-amino-2-deoxy-D-galactosyl)glycerol (34, R = H) was smoothly degraded by nitrous aoid to glycerol and 2,5-anhydro-D-talose (3S), and the W-acetyl derivative (35, R = Ac) reduced 1 molar proportion of periodate, giving neither formaldehyde nor formic acid during (84) P. J. Stoffyn and R. W. Jeanlos, Arch. Biochem. Biophyi., 52, 373 (1054). 

Non-stereospecific reduction of GDP-6-deoxy-D-/yxo-hexos-4-ulose (7c) to derivatives of 6-deoxy-D-mannose (D-rhamnose) and 6-deoxy-D-talose (see Section III,l,c) was found to occur with an enzyme from an unidentified,... 

The instability of TDP-6-deoxy-L-talose should be mentioned. When using the routine procedure for the isolation of TDP-rhamnose, a consistent loss of the 6-deoxy-L-talose nucleotide was observed. A systematic study revealed that in contrast to the rhamnose derivative, the 6-deoxy-L-talose nucleotide was extremely labile to alkali. Prolonged exposure to pH 8.0 at 37 °C resulted in significant degradation. The degradation products are TMP and 6-deoxy-L-talose monophosphate. Careful degradation studies provided experimental evidence for its identification as cyclic-l,2-monophospho-6-deoxy-L-talose. The extreme alkali lability... 

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