2-Nonulosonic acid derivatives

The stereochemical outcome of the hetero Diels-Alder reaction of the erythrose based diene with sodium glyoxylate was further rationalized by preparing the same compounds via decarboxylation of 2-carboethoxy-2-deoxy-2-ulosonic acid esters, obtained by cycloaddition with diethyl ketomalonate [146], A range of 2-nonulosonic acid derivatives - KDN analogues - were prepared including protected form of 2-deoxy-KDN,... 

The inhibitory activity of furanosyl nonulosonic acid derivative 32, and its structure with N9 sialidase, served as a starting point for the structure-based design of... 

The 4 9-bis-0- and 4>8,9-tris-0-t-butyldimethyl-silylether derivatives 2J and 8 of the biologically important neuraminic acid represent useful starting points for the synthesis of the new structurally varied nonulosonic acid derivatives 2 9 (figure 3) j5C and 21 (figure 6). Opening of the oxirsne ring of 29 with Hl. j leads to the 8-d.esoxy-8-azido-neuraminic acid derivative which corresponds completely 23. 

Branch at C-5 - The nonulosonic acid derivative 44 has been prepared by aldolase-catalysed reaction of pyruvate with 2-deoxy-2-C-hydroxymethyl-D-mannose as a possible synthon for the C-12 to C-20 sequence of amphotericin B. The latter compound was made in several steps from ethyl 2,3-dideoxy-4,5 6,7-di-0-isopropylidene-D-ara6/>io-hept-2-enoate by conjugate addition of vinylmagne-sium bromide followed by transformation of the vinyl group into a hydroxymethyl group in the key steps. ... 

The N -acetylneuraminic acid derivative (63) was converted via the iV-nitroso-derivatives (64) into the diazo-intermediate (65) which was then captured with nucleophilic reagents to give the azide (66) or the KDN (3-deoxy-D-gfycero-D-ga/flcro-nonulosonic acid) derivative (67), the stereoselectivity implying the operation of neighbouring group participation during the addition process (Scheme 10). °... 

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... 

Among all the compounds listed in Table IV under the heading Derivatives of 3-deoxy-2-nonulosonic acids, the only one reported so far as a component of living cells is 3-deoxy-D-g/ycm>D-ga/flcfo2-nonulosonic... 

The present article focuses on the occurrence and characterization of derivatives of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids and presents experimental approaches used to identify them and to elucidate the structures of the bacterial polysaccharides that contain the nonulosonic acids. Recent data on the biosynthesis of these sugars and their role in immune recognition and epitope specificity of bacterial glycopolymers are discussed. 

Fig. 17. Electron impact MS fragmentation of the fully (a, b) and partially (c, d) methylated reduced open-chain derivatives of the nonulosonic acids. [Taken from Refs. 9 (d), 14 (b), and 23 (a, c) configuration is not shown.]...

Sialic acids are a family of nine-carbon acidic monosaccharides based on 3-deoxy nonulosonic acid (Fig. 17.4, also see Chapter 5). In 1952, the biochemist Gunnar Blix introduced the term sialic acid from the Greek aaXia (salia) or saliva after isolating this molecule from the salivary gland mucin. Sialic acid is now the generic term for the family that includes derivatives with a C5-amino substituent called neuraminic acid. Neu5Ac (5) is the type of sialic acid found in humans [47],... 

S. David and A, Ihieffiy, The btominolysis reacrion of staimylene derivatives A regiospecific syndiesis of carbohydrate-derived hydroxy-ketones, J. Chem. Soc. Perkin Thins. 7 1568 (1979). A. Lubineau, H. Arcostanzo, and Y. Quenefti, Stereochemical study of cycloadditions using erythrose and threose based dienes as sources of 2-nonulosonic acid analogs, J. Carbokydr. Chem. 14 1301 (1995). 

Many hexoses were tested in both D- and L-form, resulting in the formation of nonulosonic acid analogues. Table 2 demonstrates the most common enzymatic approach to the synthesis ofNeu5Ac (entry 1) and its analogues (entry 2-12) from modified A-acetylmannosamine derivatives. 

As Neu5Ac aldolase accepts a range of substrates (more than 60 are known) in place of ManNAc, this enzyme can also used to synthesize Neu5Ac derivatives [149]. For example, if ManNAc is replaced by D-mannose, Neu5Ac aldolase can be used for the preparative-scale synthesis of KDN (3-deoxy-(5-D-g/ycer0-D-g /acto-2-nonulosonic acid Fig. 7) [150],... 

Brossmer, R. Rose, U. Kaspar, D. Smith, T. L. Grasmuk, H. Unger, F. M., Enzymic synthesis of 5-acetamido-9-azido-3,5,9-trideoxy-D-glycero-D-galacto-2-nonulosonic acid, a 9-azido-9-deoxy derivative of N-acetylneuraminic acid. Biochem Biophys Res Commun 1980, 96, (3), 1282-1289. 

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