Sugars chlorodeoxy

The potential utility of this method in the synthesis of chlorodeoxy sugars cannot be fully appraised at the present time owing to the lack of sufficient examples. 

The Preparation of Chlorodeoxy Sugars by Reaction with Sulfuryl Chloride... 

For 49, the reaction was highly successful in that a 3-O-formate ester (127) was indeed formed in a reaction period of 1 to 2 hours at room temperature with 121 followed by usual processing. Refluxing the solution for 3 to 4 hours afforded a chlorodeoxy sugar in 69-71% yield which proved to be 120 rather than the expected 3-chloro derivative (d-alio). 

It would be reasonable to expect that the decomposition of the N,N-dimethylimino ester chlorides proceeds via a bimolecular mechanism already demonstrated for the thermal decomposition of simple imino ester salts (79). In the carbohydrate series, where an isolated secondary hydroxyl group is involved, such a process would result in chlorodeoxy sugar derivatives with overall inversion of configuration, provided that the approach of the chloride ion is not sterically hindered. Further experiments are in progress in this laboratory utilizing additional model substance to establish the scope and stereochemical course of the chlorination reaction. 

Chlorodeoxy sugars by thermal decomposition of O-imino ester chlorides, synthesis of. .. 192 N-( 2-Chloro-l,l,2-trifluoroethyl) -... 

J. K. N. Jones and his colleagues have extensively studied the reaction of sulfuryl chloride with carbohydrates.21-29 This work has elucidated the stereochemical principles involved in the various transformations, and has made available a convenient and effective procedure for the preparation of chlorodeoxy sugars. Several examples of the utility of such derivatives, obtained by way of a reaction with sulfuryl chloride, in the synthesis of other rare sugars are discussed in Section III (see p. 281). In the present Section, the studies on the reaction itself are surveyed. 

Deoxyhalogeno sugars are susceptible to nucleophilic attack, leading either to displacement, elimination, or anhydro-ring formation. The ease of displacement decreases in the order I > Br> Cl > F the iodo and bromo derivatives have, therefore, been especially utilized in such reactions, although several reactions with chlorodeoxy sugars have now been reported as a result of the increased availability of these compounds. The approach delineated in Section 11,1 (see p. 227) for predicting the reactivity of sulfonic esters can be expected also to be applicable, in an approximate and qualitative way,... 

An investigation of the reduction of chlorodeoxy sugars with lithium aluminum hydride has been reported.68 In one experiment, 3-deuterio-l,2 5,6-di-0-isopropylidene-a-D-allofuranose (197) was prepared, and converted into 3-chloro-3-deoxy-3-deuterio- l,2 5,6-di-0-isopropyl-idene-a-D-glucofuranose (198) by treatment with triphenylphos-phine-carbon tetrachloride reduction with lithium aluminum hydride gave 3-deoxy-3-deuterio-1,2 5,6-di-O-isopropylidene-a-D-r/foo-hexofuranose (199), a result which established that the reduction must have occurred with, retention of configuration at C-3. 

A major part of this chapter is concerned with a discussion of a method for the synthesis of chlorodeoxy sugars by direct replacement of hydroxyl groups by chlorim... 

In Section 11.8 a discussion of the reaction of sulfuryl chloride with carbohydrate derivatives is presented, and in Section III are given some experimental procedures representative of this method for the synthesis of chlorodeoxy sugars and procedures of simple processes for the conversion of the chlorodeoxy sugars into other rare sugars. 

In 1921 Helferich [34J found that treatment of methyl a-D-glucopyranoside 18 with sulfuryl chloride in a mixture of pyridine and chloroform at 5°C afforded a compound, the structure of which was established several years later [37,38] to be that of methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-cyclic sulfate (19 Scheme 3). The cyclic sulfates are readily cleaved by dilute alkalis, or by methanolic ammonia, to give the salt of a monosulfate the hemi-ester is then desulfated by acid to yield the chlorodeoxy sugar [35,36]. Both of these reactions occur with retention of configuration [37]. 

S. Hanessian and N. R. Plessas, Reactions of carbohydrates with (halomethylene)dimethyl-iminium halides and related reagents. Synthesis of some chlorodeoxy sugars, J. Org. Chem. 34 2163 (1969). 

W. A. Szarek, A. Zamojski, A. R. Gibson, D. M. Vyas, and J. K. N. Jones, Selective, reductive dechlorination of chlorodeoxy sugars. Structural determination of chlorodeoxy and deoxy sugars by l3C nuclear magnetic resonance spectroscopy, Can. J. Chem. 54 3783 (1976). 

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