REACTIONS OF PHENYL CHLOROSULFATE AT OH-1, -4, AND -6 OF ALDOHEXOPYRANOSE DERIVATIVES. FORMATION OF 1,2-OXAZOLINE AND 4,6-CYCLIC SULFATE RINGS

Article abstract of DOI:10.1016/0008-6215(89)84091-1

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 leavinggroup affinity of a phenylsulfate substituent.This is demonstrated by a 60percent 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.