Sulfonic esters sulfonyloxy group

In a preliminary step, adjacent ester groups undergo initial hydrolysis or alcoholysis, by the base, to the oxide anion. This step is reasonable for carboxylic esters, which are rapidly hydrolyzed under the conditions usually employed, but is rather more surprising for sulfonic esters, which are usually hydrolyzed only slowly by the nucleophilic attack on sulfur required for this reaction. With these disulfonic esters, the ease of hydrolysis has been explained by the inductive effect of the adjacent sulfonyloxy group.7... 

Sulfonic esters are frequently prepared as intermediates in carbohydrate chemistry, and their widespread use in synthetic work may be attributed to several factors adequate methods are available for sulfonylation in good yield, and sulfonyloxy groups exhibit high stability under the conditions used for acetalation, glycosidation, esterification, etherification, and mercaptalation. In many cases, the substituents introduced by these reactions may also be removed with-... 

The most interesting behavior of the three dianhydrides is found in the displacement reactions of their 0-sulfonyl derivatives, and at present it seems that the reported results may be covered by three general rules. (1) Displacement of sulfonyloxy groups from the 0-sulfonates may be achieved under certain conditions, and occurs with inversion of configuration at the point of displacement. (2) Ammonia and halide ions displace sulfonyloxy groups, but alkali hydroxides (and perhaps alkoxides) merely hydrolyze the sulfonate esters by 0-sulfonyl fission, with retention of configuration. (3) Displacements by halide ions are possible only for endo sulfonyloxy groups. These rules are only tentative, and may be modified when more sulfonyloxy compounds, and their behavior to a wider variety of anions, have been studied. 

The exception noted for hydroxyl ions in rule (2) is well established for other sulfonic esters of carbohydrates, which therefore differ from simple alkyl sulfonates. An example of hydrolysis of an exo sulfonyloxy group is provided by the compound described as methanesulfonyl-monochloro-l,4 3,6-dianhydrosorbitol which must now be designated 1,4 3,6-dianhydro-5-chloro-5-deoxy-2-0-mesyl-L-iditol reaction with sodium hydroxide affords the free, hydroxy compound of the same configuration. Examples of the hydrolysis of endo sulfonyloxy groups are not available in the dianhydrohexitols, but the endo tosyloxy group in the stereochemically equivalent 3,6-anhydro-l, 2-0-isopropylidene-5-0-tosyl-D-glucofuranose (LXVII) is hydrolyzed by sodium hydroxide to the corresponding hydroxyl... 

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