Lyxose preparation

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 L-lyxose derivative was prepared from the anti-adduct 13a of 3-phenylpropanal as outlined below, and the absolute configuration was determined by comparison with the optical rotation of an authentic sample(lO) derived from D-lyxose. 

The oxime of D-lyxose has not been prepared, but L-rhamnose oxime (XX) with ithe same spatial configuration about carbon atoms 2, 3 and 4 reacts in an open-chain form when submitted to mild acetylation, and gives only the nitrile this reactivity is confirmed when the oxime is submitted to mild propionylation, for only the hexapropionyl-aWe%do-L-rhamnose oxime is produced and that in high yield. As already mentioned, the oximes of D-mannose (XXI), and D-gala-L- reawno-heptose (XXII),having the same configuration as rhamnose about carbon atoms 2, 3 and 4, react in a similar manner. 

D-Galactose. Wohl and List prepared pentaacetyl-n-galactononitrile from the oxime in 40% yield. Degradation with ammonia-silver oxide gave 40% of n-lyxose diacetamide. Hydrolysis of the diacetamide with... 

Pentapropionyl-D-galactononitrile has been prepared in 52 % yield by Gim6nez from the oxime and pyridine-acetic anhydride. Degradation with ammonia-silver oxide produced D-lyxose diacetamide in 30% yield. 

Bols and co-workers [61] synthesized isofagomine (23), a compound in which the basic hetero-atom replaces the anomeric carbon, and showed that this new type of synthetic sugar analogue is one of the strongest inhibitors of -glucosi-dase from almonds known to date. Following this innovative work, Ichikawa and Ichikawa prepared (3i ,4 ,511)-3(] )-hydroxymethylpiperidine (l,5-dideoxy-2-C-hydroxymethyl-l,5-imino-D-arabinitol, 24) [62] from D-lyxose. This was... 

Fucosidase inhibiting l,4,5-trideoxy-l,4-imino-L-lyxitol (78) was prepared [124] from D-ribose via protected 5-amino-5-deoxy-L-lyxose (79) by a chemical route. This compound, as well as the 1-aminomethyl homologue (80), obtained by Kiliani-Fischer chain extension of (79), inhibited a-L-fucosidase with K around 2 pmol/1. l,4-Dideoxy-l,4-imino-D-iditol (81) [71] was found to be a moderate inhibitor of the enzyme. 

Starting from the appropriate sulfonylated acetals 105, 106, and 107 (from 2,5-anhydro-D-ribose, -D-xylose, and -D-lyxose, respectively), the application of a method for elimination of vicinal, secondary disulfonates by reaction with sodium iodide in lV,IV-dimethylformamide in the presence of zinc112 has permitted"3 the preparation of the... 

L-fhreo-Pentos-2-ulose (9) was prepared by several procedures (see Scheme 3). In procedure A, D-galacturonic acid (14) was reduced with sodium amalgam to L-galactonic acid (15), which lactonized to L-ga-lactono-1,4-lactone (16) by removal of water. Treatment of 16 with ammonia in methanol afforded L-galactonamide (17) which, on oxidation with sodium hypochlorite, gave L-lyxose (18). Reaction of 18 with phenylhydrazine yielded the corresponding osazone (19) which, on hydrolysis, afforded 9. 

From 3-phospholenes 95, pentofuranose- and hexofuranose-type phospha sugars are prepared. Thus, all four kinds of pentofuranose-type phospha sugars (i.e., xylose, lyxose, ribose, and arabinose) are available from 3-phos-pholene as the starting material. Alkylation of 95 by a Cl unit provides the pentofuranose structure. The alkylation under LDA base and alkyl halides proceeds to give 130 (Table 13), whose czs-dihydroxylation affords 131. The... 

The details on the preparation of the glycone synthon 16 have been described in the earlier report on 3 (24). The key reactions in this synthesis is the Suarez radical fragmentation of the 1,2-O-isopropylidene furanose 17 to give the 1-O-acetyl-1,2-isopropylidene 18 (35), and acetal exchange of 18 to the phenylthio monothioacetal 16 (Scheme 2). Overall, 16 is easily obtained on multi-gram scale (ca. 20 g), in 60% yield, over five steps from commercially available D-lyxose. 

Figure 26 Comparison of the separate of PMP derivatives of aldopentose isomers on various columns (a) a column prepared by in-column 3-aminopropylation of Nucleosil silica gel (b) a column prepared by packing a commercial sample of amino silica, Develosil NH2, in an APTMS-treated capillary (c) a column prepared by packing Develosil-NH2 in an uncoated capillary. Eluent, (25 mM HEPES-NaOH, pH 6.0)-acetonitrile (2/1, v/v) sample concentration, 50 nmol in 100 pL of eluent injection, -2 kV for 3 s (from the cathodic end) applied voltage, -20 kV detection, UV absorption at 245 nm. Peaks Ara = D-arabinose, Xyl = D-xylose, Rib = D-ribose, Lyx = D-lyxose, all as PMP derivatives. (Reprinted from Ref. 111, with permission.)...

There are two lectins of distinct, sugar-binding specificity in Ulex extracts.196,225 Using ethanol fractionation, Flory225 initially discriminated between Ulex I, which is readily inhibited by L-fucose derivatives, and Ulex II, which binds /3-D-glucosides. (A comprehensive discussion of Ulex II purification and properties is presented in Section III,5.) Flory s 50-70% ethanol precipitate enriched in Ulex I, was slightly inhibited by D-arabinose, D-ribose, and D-lyxose, in addition to L-fucose.225 This preparation agglutinated human, epithelial, cheek-cells of secretory individuals only.225... 

Similar equilibrium relationships between pyranose and furanose forms apply to 5-acetamido-5-deoxy-l>lyxose. Its preparation, performed in a manner analogous to that of the D- or L-arabinose compound, by selective p-tolylsulfonylation of 0-5 of D-lyxose diisobutyl... 

R, = OH, Rj = H, R2 = OH, R4 = CHjOH in Table 3), the enantiomeric compound of the one just reported could be easily prepared. Aldol condensation products were obtained as diastereomeric mixtures from L-sugars, such as L-fucose, L-xylose, L-lyxose, and o-sugars epimeric to o-mannose relative to the 3-position, such as D-allose and o-gulose [46-48]. Table 4 lists the corresponding aldol condensation products isolated as diastereomeric mixtures. Also, 3-deoxy-D-mannose by condensation with pyruvate gave a diastereomeric mixture of 6-deoxy-KDN furanose derivatives [43]. All these results confirm that sialic acid aldolase, similar to other aldolases, exhibits broad specificity toward the electrophilic acceptor on the other hand, only pyruvate was reported acceptable as the donor [10]. But very recently, in contradiction to that, 3-fluoro-Neu5Ac and 3-fluoro-KDN could be prepared by the sialic acid aldolase-catalyzed condensation of 3-fluoropyruvate and Af-acetylmannosamine or o-mannose (Scheme 5) [47]. 

Aldopentoses such as D-ribose and L-lyxose have been prepared applying the methodology reported by Enders and co-workers [141,142,143], followed by stereoselective reduction and acetal hydrolysis (O Scheme 21). 

Thioacetal 418 can easily be prepared on a large scale from D-lyxose via intermediate 416, which is oxidized into 417 by the diacetoxy-iodobenzene/l2 system [156]. Treatment of 417 with thiophenol and BF3 -OEt2 affords 418 after methanolysis of the formate group. 

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