KDN

Deoxy-D- /rce/ o-D- a/ac7i7-nonulosonie Acid (KDN) V-Acetylneuraminic Acid Aldolase Catalyzed Preparative Aldol Additions with Pyruvate Typical Procedure27 ... 

Note, The last of the above examples is one of the possible forms of the compound referred to by the three-letter symbol Kdo (formerly the abbreviation KDO, from the previously allowed trivial name ketodeoxyoctonic acid). Similarly the symbol Kdn for the C9 sugar 3-deoxy-D-g/ycero-D-gaiacro-non-2-ulopyranosonic acid is widely used. 

As an example for continuous process design, 2-keto-3-deoxy-D lycero-D-galacto-nonosouate (KDN) (S) has been produced on a 100-g scale from D-mannose and pyruvate using a pilot-scale EMR at a space-time yield of 375 gl d and an overall crystallized yield of 75% (Figure 10.6) [47]. Similarly, L-KDO (6) can be synthesized from L-arabinose [48]. 

Chan T-H, Xin Y-C, von Itzstein M (1997) Synthesis of phosphonic add analogs of siaUc acids (Neu5Ac and KDN) as potential sialidase inhibitors. J Org Chem 62 3500-3504 Chand P, Kotian PL, Dehghani A, El-Kattan Y, Lin T-H, Hutchison TL, Babu YS, Bantia S, Elliott AJ, Montgomery JA (2001) Systematic structure-based design and stereoselective synthesis of novel multisubstituted cyclopentane derivatives with potent antiinfluenza activity. J Med Chem 44 4379 392... 

Phosphonic acid analogues 8.2 and 8.3 of both KDN and N-acetylneuraminic acid have been synthesized using the indium-mediated coupling of the lower carbohydrates with dimethyl 3-bromopropenyl-2-phosphonate (8.4) in water (Scheme 8.9).124... 

Acyclic dienes react with glyoxylic acid via an oxo-Diels-Alder reaction to give dihydropyran derivatives (Eq. 12.53). An excellent application of the oxo-Diels-Alder reaction is reported by Lubineau et al. in the synthesis of the sialic acids, 3-deoxy-Z)-manno-2-octulosonic acid (KDO) and 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN).123... 

As shown in Eq. 12.54, with glyoxylate as the dienophile, if the attack is on the si face of the diene, it would lead to the skeleton of KDO if the attack is on the re face, it would lead to the skeleton of KDN. C-Disaccharide analogs of trehalose were prepared using an... 

Yu, H. and Chen, X. (2006) Aldolase-catalyzed synthesis of beta-D-Gal-(l-9)-D-KDN a novel acceptor for sialyltransferases. Organic Letters, 8, 2393-2396. 

Aldulosonic acids are involved in many important areas of glycobiology and glycomedicine, such as /V-acetylneuraminic acid (Neu5Ac), 3-deoxy-D-glycero-v-galacto-non-2- Aosonic acid (Kdn) and 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo). 

Die Feststoffprobennahme ist bei alien automatisch arbeitenden Analysenge-raten problematisch. Auch mit dem Technicon-Feststoffprobennehmer kdn-... 

Fig. 2.2.5.4 Synthetic trisaccharides containing KDN and other NeuSAc derivatives prepared by enzymatic glycosyl transfer.

Es sei daraul hingewiesen, daB einige UbergangsmetaU-ir-Komplexe wic etwa der Fumarsaure-Fe-(COh-Komplex den Metallocenen in ihrem Ban recht ahnlich sind und in optisch aktiver Form erhalten werden kdn-nen (33). Darauf, wie auch auf die Stereochemie iiberwiegend anorganischer Komplexe (vgl. (30)), soil aber hier nicht eingegangen werden. 

Some pyrotechnic formulations Ti/KDN/NC and Ti/CsDN/NC were formulated and tested for combustion velocity, sensitivity to impact, friction and electrostatic discharge etc. The data show that both formulations are extremely sensitive to impact (the sensitivity being in the range of pure HMX and PETN ). Further, it is also seen that the Ti/KDN/NC formulation is less sensitive [145] than Ti/ CsDN/NC. On the contrary, the formulations show a moderate sensitivity to friction and electrostatic discharge. The evaluation of such systems as components in ignition formulations appear to be very promising as this may allow replacement of the heavy metal primary explosives which are toxic in nature. 

On the other hand, the reactions in dichloromethane (see Table 1 entries 9,13, and 14) were of poor stereoselectivity, although the overall yield was high. Furthermore, the formation of (1-glycoside increased with rise of reaction temperature (see Table 1, entry 14). The use of a KDN glycosyl donor 13 that is prepared by treatment [38] of 10 with thiophenol and BF3 etherate in dichloromethane, has also given results similar to those described for Neu5Ac [39]. 

The sialic acid aldolase-catalyzed condensation of D-mannose 8 and pyruvate led, in an excellent yield, to the synthesis of KDN 9 [33], a natural deaminated neuraminic acid first isolated from rainbow trout eggs [34] and then discovered in other species. The discovery that sialic acid aldolase accepts as substrates D-mannose substituted on the 2-position, even by bulky substituents such as phenyl, azido, or bromine, opened the route to novel unnatural sialic acid derivatives [35-39]. Pentoses also are substrates. N-Substituted neuraminic acids could be prepared either directly from the corresponding Af-substituted mannosamine, such as N-thioacyl derivatives [40], or after reduction and acylation of 5-azido-KDN [41]. Recently, AT-carbobenzyloxy-D-mannosamine was converted, in a good yield, into the N-carbobenzyloxy-neurarninic acid, further used as a precursor of a derivative of castanospermine [42]. 

Moreover a complete inversion of stereoselectivity has been reported with L-man-nose and L-rhamnose [49]. Table 3 lists KDO analogues with nine carbons that could be prepared as pure compounds using sialic acid aldolase. They are derived from L-hexoses belonging to l series with the R configuration at the 3- and 2-positions. In each case, KDO-type derivatives with equatorial hydroxyl on C-4 are formed, corresponding to a 4R chiral center and attack of the pyruvate from the re face of the aldehyde. Thns l-KDN... 

Recently, the enzyme from Aureobacterium barkerei, strain KDO 372, has been partially purified and used in the preparative synthesis of KDO. The pyruvate attacks from the re face of aldehyde, creating a new R chiral center at C-4 thus, the facial selectivity of KDO aldolase is complementary to the one of sialic acid aldolase. Moreover as the enzyme accepts some flexibility toward the acceptor, several other analogues with 6-, 7-, or 9-carbon atoms could be prepared, such as l-KDN and d-DAH [50]. 

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