M. Abdel-Malik, A. Perlin
Jun 15, 1989
Citations
0
Influential Citations
10
Citations
Journal
Carbohydrate Research
Abstract
Abstract In the reaction of phenyl chlorosulfate-sodium hydride with compounds having both OH-4 and OH-6 free, as in methyl 2,3-di- O -benzylaldohexopyranosides, either regioselective substitution of the primary hydroxyl group occurs, or a 4,6-cyclic sulfate is formed, depending on the experimental conditions. The addition of a 6-(phenylsulfate) substituent to the di- O -benzylglycosides appears to cause little or no interference with disaccharide synthesis at the nearby O-4 atom. Conformations of both cis - and trans -fused types of 4,6-cyclic sulfates are discussed. At an unsubstituted anomeric center, the course of reaction by phenyl chlorosulfate is determined by neighboring-group participation possibilities, and the strong leaving-group affinity of a phenylsulfate substituent. This is demonstrated by a 60% conversion of 2-acetamido-4,6- O -benzylidene-2-deoxy- d -glucopyranose into the corresponding 1,2-oxazoline derivative, in contrast to the formation of a mixture of anomeric glycosides and (1↔1) disaccharide when the O-2 substituent is benzyl.