Aldehydo Sugars preparation

Fully acetylated aldonic acids can be prepared by oxidation of aldehydo-sugar peracetates. Direct acetylation of certain aldonic acid salts is possible, and addition of cadmium salts, in particular, affords high yields of acetates. The synthesis can also be accomplished by deamination of the readily prepared, acetylated amides with nitrous acid or nitrosyl chloride. Examples of the various methods are given in Ref. 86. 

R. E. Arrick, D. C. Baker, and D. Horton, Chromium trioxide-dipyridine complex as an oxidant for partially protected sugar preparation of aldehydo and certain keto sugar derivatives, Carbohydr. Res., 26 (1973) 441 147. 

More-detailed examination of the reaction between alkylidene(and arylmethylene)triphenylphosphonium ylides and aldehydo sugars was conducted9 8 -30 in our laboratory with 2,3 4,5-di-0-cycIohexylidene-aldehydo-D-xylose (and -L-arabinose), resulting in the preparation of l-C-alkyl-3,4 5,6-di-0-cycIohexylidene-1,2-dideoxy-D-xylo(and L-ara-hino)-hex-l-enitol (27a-27d and 28a-28d, respectivelyB([Pg.236]

The previously mentioned reaction of aldehydo-s ig.aTs with two equivalents of methyl nitroacetate to prepare 4-isoxazolyl C-nucleosides (463) (Section IX,A,2) and the reverse analog 481 (Section IX,C,2) has also been used for the preparation of this type of analog from acyclo aldehydo-sugars (79BCJ2928). 

Biginelli reaction was applied for the preparation of 4-(alditol-l-yl)tetra-hydropyrimidines (984) by reacting a ternary mixture of aldehydo-sugar derivatives (34), urea or thiourea, and 1,3-dicarbonyl compounds [79MI10 81AQ(C)147 86H679] (Scheme 285). 

Osones , 2-keto-aldehydo sugars such as (18), were first prepared by Fischer by hydrolysis of the corresponding osazones (5). More recent methods involve careful oxidation of the aldose, and this was the... 

Improved yields of 3-aminoheptoses were obtained from 2-acetamido-2-deoxy-hexoses by the nitromethane route when the aldehydo-sugar (10) was used instead of the free-sugar for the condensation with nitromethane. The same authors have developed a multi-step procedure for the sequential build-up to A-acetylneuraminic acid from 2-acetamido-2-deoxy-D-mannose which can be applied to the preparation of specifically labelled compounds and stereoisomers (Scheme 8). ... 

The 1-deoxyketoses are prepared from the aldehydo-sugar acetates via the diazomethane synthesis (p. 113) 156c). 

Other 2,5-anhydro-aldehydo-sugars have been used to prepare threo- and erythro-C-qly cos ides of dihydrouracil, e.2 - (20), ... 

In the case of the oximes of the aldose sugars, the situation is more complicated because of the possibility of both open-chain and cyclic structures. That aldose oximes can react in the open-chain form follows from the formation of the nitriles and from the isolation of acylated open-chain aldose oximes as secondary products in preparation of nitriles. For example, Wolfrom and Thompson, by the action of sodium acetate-acetic anhydride on n-glucose oxime, not only obtained pentaacetyl-D-glucononitrile, in 40% yield, but also isolated a small amount of hexaacetyl-oWeAydo-D-glucose oxime (V) identical with that prepared by mild acetylation of pentaacetyl-aWe%do-D-glucose oxime (IV) whose structure was assured by its formation from pentaacetyl-aldehydo-D-glucoae (III). 

The pentoses may be converted by the conventional sequence (5) of dithioacetal formation, acetylation, and demercaptalation into the respective aldehydo-oentose 2,3,4,5-tetraacetates, which afford by Wittig chain-extension (2) the desired dienophiles. Thus aldehydo-D-arabinose 2,3,4,5-tetraacetate reacted with Ph3PCHC02Me in boiling benzene to give 90% of the pure, crystalline E-unsaturated sugar derivative 6, and the corresponding enantiomer was likewise prepared from L-arabinose. 

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