Polymerization of 1,3-anhydro-2,4,6-tri-O-benzyl-.beta.-D-glucopyranose, a substituted 2,6-dioxabicyclo[3.1.1]heptane

A Novel Polymeric Carbohydrate. Synthesis of (1→6)-2,5-Anhydro-d-glucitol by Regio- and Stereoselective Anionic Cyclopolymerization of 1,2:5,6-Dianhydro-d-mannitol

“…2,5-Anhydro-1,3,4,6-tetra-Omethyl-D-glucitol (4) and 2,5-anhydro-3,4,6-tri-O-methyl-Dglucitol (5) were synthesized from 1 as in the previous reports. 16 2,5-Anhydro-1,3,4,6-tetra-O-methyl-D-mannitol (6) was prepared by methylation of 2,5-anhydro-D-mannitol purchased from Aldrich. 19 Similarly, 2,5-anhydro-1,3,4,6-tetra-O-methyl-L-iditol (7) was synthesized from 2,5-anhydro-Liditol, which was prepared according to the method of Bock et al 19,23 Polymerization.…”

“…3,4 It was the first synthetic polysaccharide having a highly stereoregular structure similar to that of a natural polysaccharide. Using the ring-opening polymerization method, new types of polysaccharides have been synthesized, i.e., (1f3)-R-D-glucopyranan from 1,3-anhydro-β-D-glucopyranose, 5,6 (1f4)-β-D-ribopyranan and (1f5)-R-D-ribofuranan from 1,4-anhydro-R-D-ribopyranose, 7,8 and (1f6)-R-D-mannopyranan from 1,6-anhydro-β-D-mannopyranose. 9 These polysaccharides are termed artificial polysaccharides.…”

“…Schuerch and Ruckel reported the synthesis of 1,6-α-linked polyglucose, dextran, by ring-opening polymerization with 1,6-anhydro-β- d -glucopyranose. , It was the first synthetic polysaccharide having a highly stereoregular structure similar to that of a natural polysaccharide. Using the ring-opening polymerization method, new types of polysaccharides have been synthesized, i.e., (1→3)-α- d -glucopyranan from 1,3-anhydro-β- d -glucopyranose, , (1→4)-β- d -ribopyranan and (1→5)-α- d -ribofuranan from 1,4-anhydro-α- d -ribopyranose, , and (1→6)-α- d -mannopyranan from 1,6-anhydro-β- d -mannopyranose …”

Synthesis of Altrose Poly-amido-saccharides with β-N-(1→2)-d-amide Linkages: A Right-Handed Helical Conformation Engineered in at the Monomer Level

“…Polysaccharides are structurally and compositionally diverse biopolymers that perform many essential roles in biology and medicine. , Despite their importance, the synthesis of polysaccharides lags behind that of proteins and nucleic acids due to their structural complexity. , Compared to proteins and nucleic acids which are linear polymers connected by a specific type of achiral linkage, polysaccharides can be branched and possess different regio- and stereotypes of linkages , and, thus, are challenging synthetic targets. − Specifically, the challenges in synthesizing well-defined polysaccharides arise from: (1) defining the regioselectivity due to existence of multiple hydroxyl groups with similar reactivity; (2) controlling the stereochemical outcome of glycosidic bond forming reactions; , and (3) low efficiencies of glycosylation reactions . Various polycondensation and ring-opening polymerization methods have been applied to the synthesis of polysaccharides. − Among these methods, the most successful one is the cationic ring-opening polymerization of anhydrosugars developed by Schuerch et al in the 1960s and 1970s. , This method enables the synthesis of stereoregular α-1,6-linked polysaccharides with high degrees of polymerization (DP > 100), − but is less effective in preparing well-defined polysaccharides with other linkages, such as 1,4-linked and 1,2-linked polysaccharides. − Enzymatic polycondensation of sugar fluorides and sugar oxazolines represents a promising method as it affords polysaccharides with absolute control over regio- and stereospecificity. − Although this approach avoids the use of protecting groups, it requires expensive activated monomers and currently suffers from a narrow scope of transferase-mediated glycosylations …”

Catalytic Glycosylations in Oligosaccharide Synthesis

“…Peracetylated 1,2-anhydro glucose, known as Brigl’s anhydride, was used for noncatalyzed, thermal glycosylations with simple alcohols as the acceptors. − Later, Lemieux utilized this for the synthesis of maltose, trehalose, and sucrose . Anhydro sugars have also been employed as the starting material in acid-catalyzed polymerizations, − but both the thermal, noncatalyzed glycosylations and the polymerization chemistry is outside the scope of this review. This section will instead focus on catalytic activation of anhydro sugars as glycosyl donors (Figure ).…”