Glucopyranose isolation

A polyprenyl derivative of 2-acetamido-2-deoxy-4-0-(D-glucopyranosyluronic acid)-D-glucopyranose isolated from human fibroblasts transformed by simian virus 40 may be involved in the synthesis of the disaccharide rep>eating-unit of such proteoglycans as heparin. Heparan sulphate has been identified as the principal sulphated glycosaminoglycan synthesized in vitro by acinar cells from rat pancreas in the presence of sulphate ions, although the levels of heparan sulphate synthesized were very low. ... 

Apart from the number of theoretical studies on n-glucopyranose [257, 258], only one vibrational spectroscopic study of a-D-glucopyranose isolated in Ar matrix has been reported [259]. Laser spectroscopy through UV—UV and IR—UV doubleresonance techniques has contributed to the description of the conformations of some p-phenylglucopyranosides and their hydrates [219, 220, 260, 261] but these studies are limited to vibrational resolution and the structural conclusions are not totally transferable to D-glucose because of the electronic chromophore at the anomeric position. 

In spite of their easy interconversion in solution a and p forms of carbohydrates are capable of independent existence and many have been isolated m pure form as crys talline solids When crystallized from ethanol d glucose yields a d glucopyranose mp 146°C [a]o +112 2° Crystallization from a water-ethanol mixture produces p d glucopyranose mp 148-155°C [aj +18 7° In the solid state the two forms do not mterconvert and are stable indefinitely Their structures have been unambiguously con firmed by X ray crystallography... 

In spite of theii easy interconversion in solution, a and p fonns of carbohydrates are capable of independent existence, and many have been isolated in pure fonn as crystalline solids. When crystallized from ethanol, D-glucose yields a-D-glucopyianose, mp 146°C, [a]o -1-112.2°. Crystallization from a water-ethanol mixture produces P-d-glucopyranose, mp 148-155°C, +18.7°. In the solid state the two fonns do not... 

Several mono-carba-oligosaccharidic alpha amylase inhibitors, such as acarbose and its homologs, amylostatins, trestatins, oligostatins, adipo-sins, and so on, have been isolated from cultures of micro-organisms, and considerable interest in the biochemistry and chemistry of this class of inhibitors has been stimulated. The characteristic core-structure for inhibitory action is composed of a trihydroxy(hydroxymethyl)cyclohexene moiety and a 4-amino-4,6-dideoxy-D-glucopyranose moiety, bonded by way of an imino linkage at the allylic position. A similar structural unit has been found in the antibiotic validamycins. 

An alternative synthesis,by method h, was conducted by coupling 357 and 1,6-anhydro-4-0-(3,4-anhydro-6-deoxy-a-D-galactopyranosyl)-a-D-glucopyranose (392a) in 2-propanol at 120° this yielded a diastereoiso-meric mixture, from which, after the usual treatment, amylostatin (XG) was isolated in 20% yield. 

Xanthan (Figure 11) is a commercially important polysaccharide produced by the bacterium Xanthomonas campestris.187 188 The xanthan backbone consists of a P(l-4)-linked D-glucopyranose chain with a trisaccharide side chain attached at C3 to alternate glucose residues. These side chains consist of an acetylated mannose residue, a glucuronic acid residue, and a pyruvate ketal linked to a terminal mannose residue. The acetate and pyruvate content depend on the fermentation and isolation conditions used by the supplier. 

The isolation of 2,3-dimethyl-D-glucose from the hydrolysis products of certain methylated polysaccharides has been an important factor in assigning structures to these polysaccharides. From trimethyl-starch it has been recovered in about 3% yield, together with 2,3,4,6-tetra-methyl- and 2,3,6-trimethyl-D-glucopyranose, and arises from the points of linkage of the repeating chains of the amylopectin component.67,69,70 From a dimethyl-starch the yield is considerably higher (75%).71 Other sources are the methylated capsular polysaccharide of Rhizobium radici-... 

A one-pot, high-yielding synthesis of 1,2,3,4,6-penta-(9-acetyl-/ -D-( 1 -2H)glucopyranose (127) from tetra-O-acetyl-D-glucono-1,5-lactone (126) has been reported (172). Sodium borodeuteride reduction of 126, followed by in situ acetylation, gave the readily isolated and crystalline 127. The crystalline 2,4-dinitrophenyl 2,3,4,6-tetra-0-acetyl-/ -D-(l-2H)glucopyran-oside (128) was subsequently obtained from 127. 

This compound exhibits the same relationship to (3-D-fructofuranose as 1-deoxy-nojirimcin does to D-glucopyranose. In 1979, a polyhydroxyindolizidine alkaloid was isolated from the poisonous fruit of Castanospermum australe, a handsome Australian indigenous tree, and coined castanospermine (8) after its source.28 A compound subsequently isolated from the seeds of this plant was the pyrrolizidine australine (9),29 also found in Alexa leiopetala,30 along with other compounds. These discoveries increasingly supported the hypothesis that imino sugars and their structural relatives might be a fairly common family of natural products, and their widespread... 

The first synthesis of octa-0-acetyl-/3-maltose was reported by Le-mieux10 in 1953. When 1,2,3,6-tetra-0-acetyl-/3-D-glucopyranose was heated with 3,4,6-tri-0-acetyl-l,2-anhydro-a-D-glucopyranose for 13 h at 100°, it gave a mixture from which the product was isolated, after acetylation, in 8.7% yield. Octa-0-acetyl-/3-maltose has been obtained in 43.6% yield by way of condensation of 3,4,6-tri-0-acetyl-2-0-ben-zyl-/3-D-glucopyranosyl chloride with l,2,3,6-tetra-0-acetyl-/3-D-gluco-pyranose.11... 

After hydrolysis of carboxyl-reduced and partially desulfated heparin with hydrochloric acid, Wolfrom and coworkers117 isolated a disaccharide that was identified118 as 2-amino-2-deoxy-4-0-a-D-glucopyran-osyl-D-glucopyranose ( maltosamine ) hydrochloride, which gave a crystalline N-acetyl derivative (50). This structure was subsequently... 

SDMA in toluene for 20 min at 0° under an argon atmosphere gave the 5-C-(phenylphosphinyl) compound 124, which, on acid hydrolysis, afforded the 5-C-(phosphinyl)hexopyranose 125. This was treated with acetic anhydride-pyridine, to give the peracetates (126), from which crystalline l,2,4-tri-0-acetyl-3,6-di-0-benzyl-5-deoxy-5-C-[(S)-phenyl-phosphinyl]-/ -D-glucopyranose-4C1 (127) was isolated in 2% overall yield from 123 none of the other diastereoisomers of 127 were obtained. Structure 127 was established by 400-MHz, -n.m.r. spectroscopy (see Section 11,5). 

Methanol is rarely used as a solvent in the preparation of alcoholates. A monopotassio derivative of 1,2-anhydro-a-D-glucopyranose,1 8 and a sodio derivative of sucrose (see Table VIII), have been isolated from methanolic media. 

---