1.6- Anhydro sugars , preparation

Deoxy-D-jcylo hexose 6-(dihydrogen phosphate) (21) has also been synthesized (2) the reaction sequence makes use of 3-deoxy l 2,5 6-di-O-isopropylidene D-galactofuranose (16), a compound that can be easily prepared from D-glucose (2, 60). The mono-isopropylidene derivative (17) formed by partial hydrolysis of the di-ketal is converted into the 6-tosylate (18) by reaction with one molar equivalent of p-toluenesulfonyl chloride. From this the epoxide (19) is formed by reaction with sodium methoxide. Treatment of the anhydro sugar with an aqueous solution of disodium hydrogen phosphate (26) leads to the 6-phosphate (20)... 

VI. Anhydro Sugars of the Glycosan Type 1. Preparative Methods for 1,6-Anhydro Hexoses... 

An anhydro sugar which will probably find extensive synthetic use has been described by Hann and Hudson.85 This is the tricyclic compound, 3,4 1,6-dianhydro-jS-D-talopyranose (LXXIV) which is prepared by the saponification of the 4-tosyl derivative of mannosan (LXXIII). 

Comprehensive reviews of the chemistry of both the glycals [105-107] and anhydro sugars [108,109] have appeared in the recent literature. This chapter will attempt to summarize what is known about their preparation and reactivity in the formation of the glycosidic linkage and highlight recent examples to emphasize practical and strategic considerations in the choice of glycosyl donors. 

As a further illustration of the scope for use of 1,6-anhydro sugars in the preparation of uncommon sugars, the rare L-idose derivative 210 has been prepared recently and used in the preparation of oligosaccharides containing iduronic acid... 

Of other recent experiments in the chemistry of the sugars the preparation of the anhydro-sugar laevoglueosan C6H1005 by the rapid distillation of starch or cellulose in a vacuum may be mentioned (Pictet). This interesting compound possibly has the constitution I. 

The first investigation of the polymerization of an anhydro sugar was reported by Pictet21 shortly after his preparation of l,6-anhydro-/3-... 

A number of anhydro sugar derivatives have been prepared by treatment of orthoesters with mercuric bromide in nitromethane. Among them are 3-0-acetyl-l,5-anhydro-2-0-benzoyl-/3-L-arabinofuranose,68... 

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