Sugar sulfates cyclic

To gain an insight into the likely hydrolytic behavior of sulfated simple sugars and polysaccharides, Brimacombe, Foster, Hancock, Overend, and Stacey carried out a rigorous set of experiments with the cyclic sulfates of cyclohexane cis-and trims-1,2-diol as model compounds. The results were interpreted on the reasonable assumption that, in all cases, the cyclic sulfates initially afford a diol monosulfate. Examples of both S-0 and C-0 bond cleavage were encountered. A qualitative reaction mechanism was proposed for use as a working hypothesis for the hydrolysis of sugar sulfates. 

Appropriately substituted cyclic sulfates undergo an elimination reaction when treated with phosphines such as triphenylphosphine and trimethyl-phosphine in suitable solvents. The reaction is visualized to proceed via a phosphium sulfate salt as shown in Scheme 75. In the case of sugar-derived cyclic sulfates, anhydro sugars 294 were isolated (94SC1157) (Scheme 76). 

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]. 

Most carbohydrate imidazylates have good crystallization properties, and they are stable at room temperature. Common functionalities encountered in carbohydrates are compatible under the conditions of formation of imidazylates. For imidazolylsulfonylation of vicinal secondary diols, the obtained product depends on the method used. Thus, in the sulfuryl chloride method (method A), a sugar disulfonate was obtained [72], whereas the use of NaH/A[/V -sulfuryldiimidazole led to a cyclic sulfate [73],... 

P. A. M. van der Klein, W. Filemon, G. H. Veeneman, G. A. van der Marel, and J. H. van Boom, Highly regioselective ring opening of five-membered cyclic sulfates with lithium aluminium azide synthesis of azido sugars, J. Carhohydr. Chem., 11 (1992) 837-848. 

Maryanoff, B E. Structure-Activity Studies on Anticonvulsivant Sugar Sulfamales Related to Topiramate. Enhanced Potency with Cyclic Sulfate Derivatives. 3.2 1998 [37]... 

Thus, the representative reaction manner of this transformation is presented by the reactions of methyl a-D-glucopyranoside 42, as outlined in O Scheme 32. When a minimum proportion of pyridine is employed, the reaction of sulfuryl chloride with 42 produces 4,6-dichlorodeoxy sugar 54. While in the presence of an excess of p)ridine, 2,3-cyclic sulfate 55 can be formed from either compound 42 or 54. And methyl a-D-glucop)ranoside 2,3,4,6-tetra(chlorosulfate)... 

Oxolane anhydronucleosides were prepared recently from cyclic 5,6-sulfate 97 derived from diacetonoglucose. Under the basic conditions the hydroxyl group at the C-3 position was liberated and the anion thus formed attacked the C-6 position of the sugar providing the target anhydro derivative (O Fig. 24) [64]. 

This applies to a mole of seven-sugar-units and is a reasonable, added contribution shared between some 14 sulfate bonds sterically and rigidly positioned on our cyclic seven-unit oligomer. 

When used on sugars in the presence of a minimal proportion of pyridine, sulfuryl chloride produces chlorosulfate esters, instead of cyclic sulfates, but Jennings and Jones i were able to rationalize this by showing that, in the presence of an excess of pyridine, these chlorosulfate esters are sometimes converted into cyclic sulfates. For instance, methyl 4,6-0-benzyli-dene-a-D-glucopyranoside 2,3-dichlorosulfate (19) is readily converted by pyridine at 0 into the 2,3-cyclic sulfate (20), whereas, with a stronger... 

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