Osone derivatives

Hepta-0-acetyl-(2-hydroxygentiobial) gave with chlorine a mixture of non-crystalline dichlorides which, on treatment with silver carbonate, formed an acetylated osone derivative. With pyridine and acetic anhydride, this was converted into an acetate of 6-0-/3-D-glucosylkojic acid.140... 

Of unpredictable potentialities are the halogen addition compounds. Although their production and use is complicated by the existence of several isomers, they have been intermediates in the production of crystalline osone derivatives and of kojic acid. The osone derivatives, in turn, have been converted to ascorbic acid analogs through 2-ketoacids not actually isolated. 

Interest in these osone derivatives was originally stimulated49 by Hynd s60 report on certain similarities between physiological responses to D-glucosone and to insulin. The most recent studies have been part of the effort to find better routes for the preparation of ascorbic acid and its analogs.12 61 An additional point of interest was found in the ready conversion of the osone hydrates to kojic acid,6 which was attracting considerable interest as a product of the metabolism of certain microorganisms. 

Compounds of this class are characterized by their instability in acidic solutions, in which hydrolysis of the enolic ether grouping is followed by an elimination, to give unsaturated, osone derivatives, namely, 3,4-dideoxy-D-j(lj/cero-hex-3-enos-2-ulose (85, R = H) and its 6-methyl ether (85, R = Me), which are unstable, undergo ring contraction, and lose the elements of water to give, ultimately, 5-(hydroxymethyl)- and 5-(raethoxy-methyl)-2-furaldehyde (86, R = H or Me). For the monomethyl ether (84, R = H), this decomposition is complicated by a side reaction probably involving the formation of 3,6-anhydro structures. 

Arylhydrazone and bis-arylhydrazone derivatives of lactose have been prepared, and their periodate oxidation studied the formation of an osone derivative by hydrazinolysis of the bisbenzoylhydrazone is noted in Chapter 14. ... 

Oxidation. Acetaldehyde is readily oxidised with oxygen or air to acetic acid, acetic anhydride, and peracetic acid (see Acetic acid and derivatives). The principal product depends on the reaction conditions. Acetic acid [64-19-7] may be produced commercially by the Hquid-phase oxidation of acetaldehyde at 65°C using cobalt or manganese acetate dissolved in acetic acid as a catalyst (34). Liquid-phase oxidation in the presence of mixed acetates of copper and cobalt yields acetic anhydride [108-24-7] (35). Peroxyacetic acid or a perester is beheved to be the precursor in both syntheses. There are two commercial processes for the production of peracetic acid [79-21 -0]. Low temperature oxidation of acetaldehyde in the presence of metal salts, ultraviolet irradiation, or osone yields acetaldehyde monoperacetate, which can be decomposed to peracetic acid and acetaldehyde (36). Peracetic acid can also be formed directiy by Hquid-phase oxidation at 5—50°C with a cobalt salt catalyst (37) (see Peroxides and peroxy compounds). Nitric acid oxidation of acetaldehyde yields glyoxal [107-22-2] (38,39). Oxidations of /)-xylene to terephthaHc acid [100-21-0] and of ethanol to acetic acid are activated by acetaldehyde (40,41). 

The condensation reactions of aromatic o-diamines and sugars and sugar derivatives have been studied in detail and quinoxaline derivatives have been prepared recently from osones, osonehydrazones, and dehydro-L-ascorbic acidd ... 

The 2-keto acids such as 2-keto-D-galactonic acid (XXIV) can be derived from the corresponding osone (XXIII) by oxidation with bromine.10 Oxidation of L-gulosone by the same method has provided 2-keto-L-gulonic acid. The success of this oxidation depends to a large extent upon the purity of the osone subjected to oxidation and this, as previously stated, is controlled by the purity of the osazone. 

Partially methylated derivatives of D-glucosone have been prepared by decomposition of the corresponding partially methylated phenylosazones with p-nitrobenzaldehyde osones have been obtained from 5-0-methyl-D-glucose phenylosazone and from 3,4,5-tri-O-methyl-D-glucose phenylosazone in this way.22 Although 6-0-methyl-D-glucose phenylosazone is not altered by heating with benzaldehyde or piperonal in aqueous ethanolic... 

XXV). No evidence was presented by Ohle and his colleagues to support the formulation of these derivatives with a free carbonyl group, and further investigation of their structure and properties is desirable before relating them to the free osones. 

Neither of these reports has been confirmed, and, in both cases, evidence for the production of D-glucosone is incomplete, being based mainly on the preparation of non-definitive derivatives. These results are discussed more fully in the Section dealing with the biological significance of the osones. 

LaForge and Hudson194 prepared an osone from the phenylosazone obtained from sedoheptulose (D-aZ(ro-heptulose). The osone reduced Fehling solution strongly, formed the original osazone with phenylhydrazine, and gave a crystalline derivative with o-phenylenediamine. 

These compounds are formally derived from aldoses by oxidation of a secondary hydroxyl group to a ketone group. The well-known aldos-2-uloses (usually termed simply aldosuloses or osones in former usage) have long been known in the form of their bis(hydrazone) derivatives, the osazones. Deoxyaldosuloses have been implicated as intermediates in a variety of degradation reactions. Aldos-3-, -4-, and -5-uloses have been prepared, principally as intermediates for synthesis. 

The acetylated 2-hydroxyglycals derived from D-galactose9 and gentiobiose13 have also been chlorinated but without isolation of crystalline dichlorides. Conversion of the sirups to the respective osone hydrates was made without isolation of the intermediates. The osone hydrate from gentiobiose failed to crystallize, but the strong reducing power of the sirup indicated its presence. 

Osone hydrates have been prepared from 2,3,4,6-tetra-0-acetyl-(2-hydroxy-D-glucal)1 and from the corresponding derivatives of 2-hydroxy-D-galactal,9 2-hydroxyceIlobial13 and 2-hydroxygentiobial.13 Hydrolysis of the dichloride may be effected simply by the addition of a little water to its solution in ether or benzene, but more often silver carbonate or sodium bicarbonate is added to neutralize the hydrogen chloride produced. Sodium and potassium carbonate are too alkaline and result in yellowing of the reaction mixture. A yield of 90% of the theoretical amount of osone hydrate was obtained from the crystalline dichloride derived from D-glu-cose. However, the crystalline dichloride derived from cellobiose resisted hydrolysis (see the previous Section). Nevertheless, the cellobiosone hydrate was prepared from the sirupy mother liquor. In any case, yields on the basis of the entire, chlorinated substances were low.1613... 

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