Uncommon sugars

As a further illustration of the scope for use of 1,6-anhydro sugars in the preparation of uncommon sugars, the rare L-idose derivative 210 has been prepared recently and used in the preparation of oligosaccharides containing iduronic acid... 

The first possibility mentioned above, that of induction by cell/ inducer contact, may be plausible in the case of cellulose, but it does not appear to account for induction by soluble sugars such as sophorose or lactose. If the cell possesses certain sites on the surface which recognize specific sugar linkages, then why is sophorose not an inducer in other cellulolytic migroorganisms when it is an excellent inducer in T. reesei And why are other uncommon sugars, which possess linkages similar to that of cellulose and sophorose, not inducers (32) ... 

The structure contains a number of uncommon sugars, including Kdo (Figure 1.9), apiose (Figure 1.15), Dha (2-keto-3-deoxy-D-/yxo-heptulosaric acid) and aceric acid, AceA (3-carboxy-5-deoxy-L-xylose) (Figure 4.64). Side-chain structures are shown in Figures 4.63, 4.65 and 4.66. 

The opposite stereochemical outcome is observed when reduction is performed on the fully oxidized 23 26 In their synthesis of uncommon sugars from furanaldehyde, Wang and co-workers discovered that the stereochemical outcome of the Luche reduction can be manipulated by changing the temperature of the reaction. As shown below, Luche conditions successfully reduced the fully unsaturated ketone producing intermediate 24 in 75% yield. At 0 °C, a separable mixture of the two lactones 24 and 25 was obtained in a 2 1 ratio. However, execution at -78 °C solely yielded lactone 24. 

Uncommon sugars and their conjugates to natural products. 

Uncommon Sugars and Their Conjugates to Natural Products... 

Figure 1. Uncommon sugar library (a) L-Sugars (b) D-Sugars (Boxedcompounds are currently available in Wang s lab).

The cytotoxicities of these six compounds (Figure 7) were examined in colon cancer cell line SW620 cells. The results in Table II indicated that the aglycon, DNR-A, exhibited 70 to 100-fold lower cytotoxicity than daunorubicin derivatives with various uncommon sugars. This suggests that sugar structure in daunorubicin plays a critical role in determining its anticancer activity. 

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