Syntheses of derivatives of lacto-N-biose. I. 4,6-Di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-α,β-D-glucopyranosyl chloride

Abstract

Procedures are reported for the synthesis of 4,6-di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-α,β-D-glucopyranosyl chloride, a reagent useful for the reliable introduction of β-D-Galp-(1 → 3)-β-D-GlcNAcp units (lacto-N-biose 1 units) into oligosaccharide structures. A benzyl glycoside intermediate is hydrogenolyzed to the alcohol which is subsequently converted to the glycosyl chlorides by use of the Vilsmeier reagent in the presence of sym-collidine. A comparison is made of the oxazoline method for the preparation of β-glycosides from 2-amino-2-deoxysugars and the phthalimido procedure developed in this laboratory.

Synthesis of β-C-Glycosides of N-Acetylglucosamine via Keck Allylation Directed by Neighboring Phthalimide Groups

“…The use of only 3 molar equiv resulted in a 30% yield of compound 4 , with the thermal elimination product 5 accounting for the remainder of the isolable mass. We also examined glycosyl chloride 6 as a substrate for radical-promoted β- C -glycosylation …”

Development of Highly PotentD-Glucosamine-Based Chiral Fluorescent Labeling Reagents and a Microwave-Assisted β-Selective Glycosidation of a Methyl Glycoside Reagent

“…256-258 C, ½ D þ120 (C ¼ 1:1, CHCl 3 ), was prepared from D-glucosamine hydrochloride and 2,3-anthracenedicarboxylic anhydride in two steps in 68% yield, using a procedure similar to that used for preparing N-phthalimido-O-acetyl glucosamine. 11,12) Although the reaction conditions gave a mixture of , -acetates ( : ¼ 1:2) with phthalimide derivative, 11,12) they gave onlyacetate with anthraceneimide derivative. This result can be ascribed to the difference in steric bulkiness between the phthalimide and anthraceneimide groups because the conditions gave a mixture of , -acetates ( :…”

“…The selective -glycosidations can be ascribed to the neighboring-participation of the anthraceneimide group at the 2-position, as was proposed with the glycosidation of 2-phthalimido derivatives. 11,12) Although the yields are acceptable for our analytical purposes, these glycosyl bromides are not stable enough to be kept in desiccators for long. Hence, we sought other glycosidation methods.…”