Sulfones, sugar

Alkyl sulfonic acids Sulfonated sugar preparations Anion exchange Suppressed conductivity... 

Alkaline saponification of polymer-bound sugar ester did not proceed very smoothly, but when polymer-sulfonate sugar esters were employed, the cleavage involving detosylation and O-alkyl fission of the sulfonate ester (KOAc-DMF) proceeded smoothly (Guthrie et at., 1973), producing 0-acetates. From this it may be concluded that the OAc group is not affected under these conditions. 

Cyclamate is about 30 times (8% sucrose solution sweetness equivalence) more potent than sugar. Its bitter aftertaste is minor compared to saccharin and acesulfame-K. The mixture of cyclamate and saccharin, especially in a 10 1 ratio, imparts both a more rounded taste and a 10—20% synergy. Cyclamate (6) is manufactured by sulfonation of cyclohexylamine (7). Many reagents can be used, including sulfamic acid, salts of sulfamic acid, and sulfur trioxide (74—77). 

The Preparation of Halodeoxy Sugars by Displacement of Sulfonate Esters... 

Another deviation from the normal displacement reaction of primary tosylates occurs in nucleoside derivatives (39, 81) where cyclonucleosides and anhydronucleosides are formed by participation of a nitrogen atom (as in purine nucleosides) and oxygen atom (as in pyrimidine nucleosides ), respectively. Iodonucleosides can result from these reactions only if these cyclic compounds are prone to attack by iodide ion. Several new examples of unexpected reactions during the solvolysis of sulfonate esters in sugar derivatives have been recorded in the past few years (2, 4,5,7,15,44,62,63,94). 

Metal halide salts other than sodium iodide have been used sparsely to prepare halodeoxy sugars from sulfonate esters. Lithium chloride (107) and lithium bromide (33) have found limited application. Potassium fluoride (dihydrate) in absolute methanol has been used (51, 52) to introduce fluorine atoms in terminal positions of various D-glucose derivatives. The reaction is conducted in sealed tube systems and requires... 

The use of tetra-n-butylammonium fluoride (54) in an aprotic solvent such as acetonitrile may be more advantageous. Foster and colleagues (19, 37) have effected an SN2 type of reaction using this reagent in the conversion of l,2 5,6-di-0-isopropylidene-3-0-p-tolylsulfonyl-D-allofura-nose into the C-3 epimeric fluorodeoxy derivative. Note that whereas potassium fluoride is ineffective in displacing secondary sulfonate esters in sugars, tetra-n-butylammonium fluoride is capable of effecting a displacement with Walden inversion even in a furanose drivative. 

Perhaps the earliest report of the replacement of a sulfonate ester attached to a secondary carbon atom in a sugar derivative was that of Helferich (53). Under quite drastic conditions (sodium iodide in acetone, 105°C., 72 hours, sealed system) the 4-mesylate derivative 9 was converted into a crystalline 4-deoxy-4-iodo sugar derivative 10 in 46% yield. Although the position of the iodine atom was established, the configuration at C-4 was not known. 

The reactivity at the C-4 position of hexose and hexoside sulfonates has been demonstrated in the gluco and galacto series and could undoubtedly be extended to other sugars as well. In another example (25), methyl 2,3-di-0-benzoyl-4-0-p-tolysulfonyl-a-D-glucopyranoside (18a) was treated with potassium thiocyanate in N,N-dimethylformamide at 140°C. for 9 hours to give the C-4 epimeric thiocyanato derivative 19 in 34% yield. The corresponding 4-p-bromobenzenesulfonate (18b) however, afforded a 55% yield of 19 in only 2% hours of reaction time. 

Triazoline imino sugar derivatives 297 that are prospective glycosidase inhibitors have been prepared as single diastereomers in high yield via an lAOC reaction of in situ generated azido alkene 296 (Eq. 32) [78]. m-CPBA oxidation of the dithioacetal groups in the 0-acetylated 5-azido-5-deoxydibenzyl dithio-acetal of o-xylose or D-ribose 294 to the bis-sulfone 295, followed by loss of HOAc between C-1 and C-2 provided the lAOC precursor 296. 

The displacement is effected preferentially by a nucleophilic group already in the molecule. Thus, in the above reaction there is no evidence that OTs- is displaced by the external ion, OMe-, under the conditions used, nor is there ahy displacement of OTs- of a sugar sulfonate by OAc-, Buch as was found to occur when the sulfonate of a monohydric aliphatic alcohol was treated with potassium acetate.11... 

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