Galactose sulfonyl chlorides

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]. 

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... 

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... 

---