Aldoses, 2-amino-2-deoxy derivatives

The cyclic acetals have been of great assistance in the preparation of, for example, methylated sugars, - deoxy sugars, and amino-deoxy sugars. The specific syntheses of many di- and tri-saccharides have been described - in these, a suitable acetal of the aldose is caused to react with a poly-O-acetylglycosyl halide or a bromo- or chloro-hydrin derivative. 

Aldoses containing acetamido-, amino-, deoxy-, and thio-groups have been examined by g.l.c. of their peracetylated aldononitrile derivatives. Chemical... 

The generic term monosaccharide (as opposed to oligosaccharide or polysaccharide) denotes a single unit, without glycosidic connection to other such units. It includes aldoses, dialdoses, aldoketoses, ketoses and diketoses, as well as deoxy sugars and amino sugars, and their derivatives, provided that the parent compound has a (potential) carbonyl gTOup. 

The Knovenagel condensation under basic conditions was first investigated with D-glucosamine chlorhydrate (28.HC1) as the sugar. The condensation of this reducing amino sugar with pentane-2,4-dione 1 in aqueous acetone in the presence of sodium carbonate afforded the pyrrole derivative 29 in 85% yield [99] (Scheme 5). The reaction was extended to other 2-amino-2-deoxy-aldose and carbon nucleophiles [100-104]. 

An account of the methods of synthesis of amino sugars has been given in an earlier Volume of this Series1 attention is devoted in this Section to methods recently developed. Several general methods have been employed for the synthesis of 2-amino-2-deoxy-aldoses these respectively involve direct amination of suitable sugar derivatives, interconversion of sugar series, and ascent or descent of a series with or without concomitant amination or molecular rearrangements. 

The oxidation of aldose phenylosazones to aldos-2-uloses (osones) and the g.l.c. separation of the TMS ethers of the products have been examined in the cases of the D-f/ reo-pentose, D-arabino-, D-lyxo-, L-xy/o-hexose compounds, and two disaccharide derivatives. A new approach to the synthesis of ketonic carbohydrate derivatives involves the treatment of amino-compounds with sterically hindered quinones to prepare imines which rearrange as shown in Scheme 1 to give products which undergo hydrolysis to ketones. The method gave the 2- and 3-ulosides, respectively, when applied to methyl 2-amino-2-deoxy-a- and 3-D-glucopyranoside and methyl 3-amino-3-deoxy-j3-D-allo-furanoside. ... 

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