Galactose sulfonylation

Alkyl (or acyl) derivatives of the 6-amino-6-deoxy carbohydrates are examples of derivatives in which the hydrophilic and hydrophobic moieties are linked at other positions than C-1. Thus 6-amino-6-deoxy-D-galactose derivatives 34 were prepared from l,2 3,4-di-0-isopropylidene-6-0-tosyl-a-D-galacto-pyranose by the following reactions (1) substitution of the leaving group at C-6 by a phthaloyl function, (2) hydrazinolysis to afford a 6-amino-6-deoxy intermediate, (3) reaction of acyl or sulfonyl chlorides at the amino function, (4) deprotection of the acetal rings to afford the expected glycolipid 34 [56]. 

Despite the immediate application of unimolar sulfonylation for the preparation of many w-sulfonic esters of sugar derivatives, a kinetic study of the reaction was not made until 1942 Hockett and Downing136 then found that, with p-toluenesulfonyl chloride-pyridine at 23° 2°, the time to half-esterification for a mole of l,2 3,4-di-0-isopropylidene-D-galactose (with a primary hydroxyl group) is 0.272 hours (see Fig. 2), whereas for l,2 5,6-di-0-isopropylidene-D-glucose (with a secondary hydroxyl group) it is 20.2 hours (see Fig. 3). That is, after about 120 minutes, nearly all of the compound with the free primary hydroxyl group... 

Soon after the application of sulfonylation to sugar derivatives, the action of hydrazine17 on l,2 5,6-di-0-isopropylidene-3-0-tosyl-D-glucose, and of ammonia297 on l,2 3,4-di-0-isopropylidene-6-0-tosyl-D-galactose, was found to proceed similarly. Immediate application of this principle to preparation298 of aminated cellulose derivatives,86299 of possible... 

The rates of reaction of diisopropylidene derivatives of L-sorbose, D-glucose and D-galactose with an excess of triphenylmethyl chloride in pyridine, have been studied.162 Similar studies were then conducted on the reactivity of these diisopropylidene derivatives with p-toluene-sulfonyl chloride.168... 

The well known difference between galactose-6-sulfonates and most other primary sulfonates in reactivity toward nucleophiles270 has received further attention. The resistance of l,2 3,4-di-0-iso-propylidene-6-O-sulfonyl-D-galactoses toward displacements, initially observed with iodide, has also been found with fluoride,267 271 meth-oxide,194 and thiolacetate.272-273 However, l,2 3,4-di-0-isopropylidene-6-O-p-tolylsulfonyl-D-galactose (9, R = Ts) reacts with potassium... 

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