Of halogenated sugars

Many other examples of the use of halogenated sugar analogues in glycoprotein research could be cited, including additional rational approaches to chemotherapeutic agents. These are discussed in more detail in recent reviews147,151. 

X. Reaction of Halogenated Sugars with Sodiiun Cobalt... 

The question of halogen substitution has not arisen here. The earlier investigators attempted the isolation of halogenated sugars as possible intermediates in the oxidation reactions. None were found. In the case of some simpler alcohols and hydroxy aldehydes and ketones, substitution has been found to occur and the products have been hydrolyzed to oxidation products. Since most of these halogenated compounds have been formed in non-aqueous systems, it seems doubtful that substitution would occur readily in the presence of water without decomposition of the halogenated products. 

More recently a group of halogenated sugars have been found to have similar properties to the bifunctional alkylating agents 1. 1,6-Dibromo- 1,6-dideoxy-D-mannitol, for example (DBD, Mitobronitol 10) is now in clinical use, but it is believed to act at least in part by transformation in vivo to the bis epoxide... 

Two symposia reports have appeared on issues associated with sweetness, the first dealing with natural and artificial sweetners, which included consideration of theoretical, structural and physical chemical correlations," while the second focused on the sweetness of halogenated sugar derivatives. A lectoe on the synthesis of glycothanes as receptors in novel compounds derived from a,a-trehalose has been published. ... 

Note The dipping solution can also be employed as spray reagent. The detection limits per chromatogram zone are reported to be 1 — 5 pg substance [1] for the oxyacids of halogens and ca. 10 pg substance for reducing sugars [4]. 

Despite several attractive features in this method of direct halogen introduction and the obvious applications in the synthesis of deoxy sugars, its uses have not been further exploited by other groups of workers. Some new related methods have become available which reportedly eliminate the difficulties previously encountered such as rearrangement, unreactivity due to steric hindrance, and phosphonate ester formation. The reaction is based on the observation (28) that triethylphosphine reacts with ethanol and carbon tetrachloride to give ethyl chloride, chloroform, and triethylphosphite. In a new adaptation (76, 77) of this... 

It is puzzling that the chlorine and other halogen substituents are not known to enhance the sweetness of other sugars, such as methyl -d-glycopyranosides, a,a-trehalose, maltose, or lactose. On the contrary, all of the deoxyhalo sugar derivatives tasted were extremely bitter. The high sweetness of the deoxyhalosucroses is clearly inexplicable in terms of either... 

The search for new methods of synthesis of halogenated carbohydrates continues to be an active area of investigation. The compounds are of utility as synthetic intermediates, and many of them are of intrinsic value in biochemistry and pharmacology. In the present Chapter methods for the synthesis of deoxyfluoro sugars and glycosyl fluorides are discussed. 

The increased availability of methods for the preparation of unsaturated sugars107 has stimulated interest in addition reactions of these compounds the use of unsaturated carbohydrate derivatives as precursors for specifically halogenated sugars has been widely exploited. 

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