L-Fructose

FIGURE 7.4 D-Fructose and L-fructose, an enantiomeric pair. Note that changing the configuration only at C5 would change D-fructose to L-sorbose. 

L-fructose and two-step synthesis of L-iminocyclitols. It remains to be seen how general the borate effect is. 

Franke, D., Machajewski, T., Hsu, C.-C. and Wong, C.-H. (2003) One-pot synthesis of L-fructose using coupled multienzyme systems based on rhamnulose-1-phosphate aldolase. The Journal of Organic Chemistry, 68 (17), 6828-6831. 

Fig. 1.—Fischer s Total Synthesis of D-Glucose, D-Mannose, and D-Fructose and of L-Glucose, L-Mannose, and L-Fructose.

Figure 8 Dependence of the relative CL intensity upon the final molar concentration of HTAH observed from the reaction of 3.3 X 1CT4M lucigenin with (A, solid line) 200 mg/L glucose and ( , dashed line) 48 mg/L fructose. (From Ref. 38 with permission.)...

Among many other methods for epoxidation of disubstituted E-alkenes, chiral dioxiranes generated in situ from potassium peroxomonosulfate and chiral ketones have appeared to be one of the most efficient. Recently, Wang et /. 2J reported a highly enantioselective epoxidation for disubstituted E-alkenes and trisubstituted alkenes using a d- or L-fructose derived ketone as catalyst and oxone as oxidant (Figure 6.3). 

Sugiyama, M., Hong, Z., Whalen, L.J., Greenberg, W.A. and Wong, C.-H., Borate as a phosphate ester mimic in aldolase-catalyzed reactions practical synthesis of L-fructose and L-iminocyclitols. Adv. Synth. Catal. 2006, 348, 2555 - 2559. 

One-step Synthesis of L-Fructose Using Rhamnulose-l-phosphate Aldolase in Borate Buffer... 

A practical, inexpensive one-step procedure was developed for the RhaD-catalyzed gram-scale synthesis of L-fructose. The requirement for DHAP as the donor substrate was circumvented by use of borate buffer, presumably by in situ formation of borate esters as a phosphate ester mimic. Racemic glyceraldehyde was also used, as the enzyme preferentially accepted the L-enantiomer as a substrate. The method can also be apphed to other products, including L-rhamnulose, and towards a two-step synthesis of L-iminocychtols. ... 

L-Fructose from L-fructose, L-mannose, L-psicose CaY Water [224]... 

ReiSig and Hausherr synthesized (-)-preussin in ten steps starting from L-fructose. The chiral alkoxy allene 143 was formed as a mixture of diastereoisomers which differed in the configuration of the chiral axis [77]. 

In 1996, ketone 26 was reported to be a highly effective epoxidation catalyst for a variety of trans- and trisubstituted olefins [53]. Ketone 26 can be readily synthesized from D-fructose by ketalization and oxidation (Scheme 2) [54-56]. The enantiomer of ketone 26 (ent-26) can be obtained by the same methods from L-fructose, which can be obtained from L-sorbose [57, 58]. 

The synthehc applicability of arsenates is restricted by their toxicity that avoids the green aspect of the enzymatic processes. Wong et al. have shown that the use of inorganic borate buffer allows L-rhamnulose-l-phosphate aldolase (Rha-IPA) to accept DHA as substrate, although the of the reaction is about 50 times lower than with the natural substrate [10]. In spite of this fact, these authors have successfully used this approach for the one-step synthesis of L-fructose and L-rhamnulose, and for the facile two-step synthesis of several L-iminocyclitols. 

Rare or unnatural monosaccharides have many useful applications as nonnutritive sweeteners, glycosidase inhibitors and so on. For example, L-glucose and L-fructose are known to be low-calorie sweeteners. In addition, rare or unnatural monosaccharides are potentially useful as chiral building blocks for the synthesis of biologically active compounds. Therefore, these compounds have been important targets for the development of enzymatic synthesis based in the use of DHAP-dependent aldolases alone or in combination with isomerases. Fessner et al. showed that rare ketose-1-phosphates could be reached not only by aldol addition catalyzed by DHAP-dependent aldolases, but by enzymatic isomerization/ phosphorylation of aldoses [35]. Thus, for example, L-fructose can be prepared... 

Scheme 4.14 L-Fructose synthesis starting from glycerol and DHAP using a multi-enzyme system with galactose oxidase, Rhal PA, catalase and APase.

The first, total synthesis of sugar-like compounds was performed as early as 1861 in that year, Butlerov2 reported the formation of methylenitan on treatment of aqueous formaldehyde with calcium hydroxide. The first, defined sugar derivative, DL-mannitol ( a-acrit ), was obtained by Emil Fischer and Tafel,3 and the first, optically active, totally synthetic sugars, D- and L-mannose and D- and L-fructose, were also prepared by Fischer.4... 

D,L-Mannitol has been obtained by sodium amalgam reduction of D,L-mannose. The identical hexitol is formed from the formaldehyde polymer, acrose, by conversion through its osazone and osone to D,L-fructose (a-acrose) followed by reduction (83). 

Recognition systems in animal cells have been extensively reviewed. Some examples include the D-galactose- and L-fructose-recognition system of mammalian hepatocytes,233,234 the 2-acetamido-2-deoxy-D-glucose-recogni-... 

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