Regioselectively Modified Stereoregular Polysaccharides IX. A Synthetic Polysaccharide Having One Hydroxyl Group in Its Repeating Unit, 2,4-Dideoxy-(1→6)α-D-threo-hexopyranan

Kobayashi, Kazukiyo; Sumitomo, Hiroshi; Ichikawa, Haruo; Sugiura, Hiroaki

doi:10.1295/polymj.18.927

Cited by 8 publications

(5 citation statements)

References 23 publications

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“…This supports the reported diagnostic character of the weak Lewis acid BF 3 0Et 2 for the polymerization of 1 ,6-anhydrosugar derivatives; it is an 876 effective initiator for 4 7 and other monomers11 -13 deoxygenated at the C-2 position, but uneffective for DL-5 9 and others 14 having a benzyloxy substituent at this position.…”

Section: Polymerization Reactivity Of 1 6-anhydro-2-0-benzyl-3 4-disupporting

confidence: 84%

“…The debenzylation and work-up procedures were similar to those described previously. 7 Characterization 1 H and 13 C NMR spectra were recorded on a Japan Electron Optics Laboratory JNM-FX-200 Fourier transform NMR spectrometer operating at 200 and 50 MHz, respectively. Optical rotations were determined at 25°C on a Japan Spectroscopic Co. DIP-181 digital polarimeter using a water-jacketed 1-dm cell.…”

Section: Debenzylationmentioning

confidence: 99%

“…This is in contrast to the polymerization of 4 in which the content of {3-structural unit in the polymer increased at a later stage of polymerization. 7 Inversion of a to {3-structure is assumed to proceed through an acetal-exchange reaction involving the polymer chain and oxonium ion in the growing chain end. 17 The attack of oxonium ion on the acetal C-1 carbon in polymer 2 would be sterically hindered by the axially-oriented benzyloxy group in position 2.…”

Section: Polymerization Reactivity Of 1 6-anhydro-2-0-benzyl-3 4-dimentioning

confidence: 99%

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Regioselectively Modified Stereoregular Polysaccharides X. Equilibrium Polymerization of 1,6-Anhydro-2-O-benzyl-3,4-dideoxy-β-D-threo-hexopyranose

Ichikawa

Kobayashi

Okada

et al. 1987

Polym J

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ABSTRACT:A synthetic linear polysaccharide having one axial hydroxyl group in position 2 in each repeating unit, 3,4-dideoxy-(1--->6)-IX-D-threo-hexopyranan (3), was synthesized by cationic ring-opening polymerization of I ,6-anhydro-2-0-benzyl-3,4-dideoxy-j)-D-threo-hexopyranose (1), followed by debenzylation. The polymerization of I using phosphorus pentafluoride as initiator at temperatures ranging from -60 to ooc gave the stereoregular polymer with an IX-anomeric configuration, 2-0-benzyl-3,4-dideoxy-(1--->6)-IX-D-threo-hexopyranan (2). The apparent polymerization rate and copolymerization reactivity of 1 were high, but the polymer yield was relatively low owing to the high equilibrium monomer concentration of 1 ([ML =0.31-0.54moll-1 at -60"C). It is suggested that the free energy change in polymerization is negative but small because the benzyloxy group oriented equatorially in the monomer is converted to the axially oriented one in the course of polymerization. Debenzylation of 2 with sodium metal in liquid ammonia afforded a white powdery polysaccharide identified as 3. On the basis of the 13 C NMR spectrum of the optically active polysaccharide 3 consisting of D-enantiomer unit, an unambiguous assignment was made on diad tacticities of D,L-enantiomeric units in the racemic polymer reported previously.

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Section: Polymerization Reactivity Of 1 6-anhydro-2-0-benzyl-3 4-disupporting

confidence: 84%

Section: Debenzylationmentioning

confidence: 99%

Section: Polymerization Reactivity Of 1 6-anhydro-2-0-benzyl-3 4-dimentioning

confidence: 99%

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Regioselectively Modified Stereoregular Polysaccharides X. Equilibrium Polymerization of 1,6-Anhydro-2-O-benzyl-3,4-dideoxy-β-D-threo-hexopyranose

Ichikawa

Kobayashi

Okada

et al. 1987

Polym J

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“…The high reactivity of 1 relative to 4 was probably due to the 2,4-dideoxygenated anhydro structure. 10 Both the acetal oxygen of the monomer and the trialkyloxonium ion of the growing terminal in 1 are less sterically hindered and more basic and nucleophilic than those in the corresponding dibenzyloxylated compound (4). On the other hand, a low reactivity of 1 relative to 5 was explained by assuming that the large side-chain group hindered both reaction centers.…”

mentioning

confidence: 99%

Synthesis of a comb-shaped branched polysaccharide via ring-opening polymerization of a reactive anhydro disaccharide derivative

Ichikawa¹,

Kobayashi²,

Sumitomo³

1990

Macromolecules

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This paper deals with a comb-shaped branched polysaccharide, which has a linear backbone and pendant monosaccharide units regularly substituted on each sugar unit in the main chain.',' Naturally occurring polysaccharides often have branched structures, and their physical and biological functions are influenced by the nature of the b r a n~h e s .~ It has also been noted that branched oligosaccharides on glycoproteins and glycolipids in cell surface membranes are key participants in cell-cell recognition during de~elopment.~ In these respects, welldefined comb-shaped polysaccharides are expected to serve as model substances for physicochemical and biological studies and as cell-specific biomedical materials using carbohydrates as a recognition marker.5,6Synthesis of comb-shaped branched polysaccharides has been attempted by two different routes via ring-opening polymerization of anhydro sugar derivatives: (1) polymerizatioin of anhydro disaccharide derivatives followed by deprotection',' and (2) synthesis of regiospecifically protected linear polysaccharides followed by stereoselective glycosidation and d e p r o t e c t i~n .~,~ The former route is favorable for the synthesis of polysaccharides that are substituted completely and stereospecifically with monosaccharide moieties. However, anhydro disaccharide derivatives seem less reactive in polymerization than the corresponding anhydro monosaccharide deriva-ti~es,','*~and hence highly reactive disaccharide anhydrides are required to lead to high molecular weight polysaccharides.In this paper, we gave attention to the high polymerization reactivity of dideoxygenated anhydro ring structures'O and to the role of a P-galactopyranose unit as a recognition marker. According to Scheme I, these two moieties were coupled to give 1,6-anhydro-3-0-(2,3,4,6-tetra-0-benzyl-~-~-galactopyranosyl)-2,4-dideoxy-~-~-threo-hexopyranose (1). The ring-opening polymerization of 1 followed by deprotection of the resulting polymer (2) was carried out, and a well-defined comb-shaped polysaccharide, 2,4-dideoxy-3-0-(P-~-galactopyranosy1)-(1-+6)a-D-threo-hexopyranan (3) was obtained. The polymerization reactivity of 1 is discussed in comparison with those of analogous anhydrides and their parent compounds including 1,6-anhydro-2,4-di-O-benzyl-3-0-(2,3,4,6-tetra-~-benzy~-~-~-gaiactopyranosy~)-~-~-g~ucopyranose (41, 1,6-anhydro-3-O-benzyl-2,4-dideoxy-P-~threo-hexopyranose (5)," and 1,6-anhydro-2,3,4-tri-Obenzyl-s-D-glucopyranose (6). BnO ,OBn OBn OBn OBn OBn 4 5 6 0024-9297 I 9 0 12223-1884$02.50 I O Results and Discussion Synthesis of a Comb-Shaped Branched Polysaccharide, 2,4-Dideoxy-3-0-(&~-galactopyranosyl)-(1-.6)-a-~-thr~hexopyranan (3). Polymerization data of 1 are summarized in Table I. A relatively large amount of the initiator was required. The molecular weight of the disaccharide derivative was high (MW = 653), and hence the monomer concentration could not be made higher than those employed. The polymerization of 1 at -78 O C was more satisfactory than that at -60 "C in terms of pol...

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“…Sci., Part C 1964, 6, 33. (19) Jones, A. T. Polymer 1966, 7, 23. (20) Anderssen, R.; Bloomfield, P. Numer.…”

Section: References and Notesmentioning

confidence: 99%

Unusual anionic desalting oligomerization of alkali metal salts of bromo-substituted bicyclic oxalactam

Hashimoto¹,

Sumitomo²,

Suzuki³

1987

Macromolecules

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2797calorimetry curves of samples and components, and X-ray diffraction scan of sample I1 component 1 (29 pages). Ordering information is given on any current masthead page. In this paper the periodic group notation in parentheses is in accord with recent actions by IUPAC and ACS nomenclature committees. A and B notation is eliminated because of wide confusion. Groups IA and IIA become groups 1 and 2. The d-transition elements comprise groups 3 through 12, and the p-block elements comprise groups 13-18: (Note that the former Roman number designation is preserved in the last digit of the new numbering: e.g., I11 -3 and 13.)ABSTRACT The oligomerization of sodium and potassium salts of a new bromo-substituted bicyclic oxalactam, 4(e)-bromo-8-oxa-6-aabicyclo[3.2.l]odan-7-one (I), proceeds in Nfl-dimethylformamide or dimethyl sulfoxideat 0 or 25 "C with elimination of alkali metal bromide to give novel oligomers 2 having a bicyclic oxalactam ring in each monomer unit. Oligomers similarly obtained from mixtures of 1 with its sodium salt had lower average molecular weight. Two diastereomeric dimers and a trimer were isolated by fractional elution from a preparative silica gel column. Structural analyses indicate that the oligomerization proceeds with high enantiomeric selectivity and complete retention of the configuration of the bridgehead methine carbon atom adjacent to nitrogen. Possible mechanisms for this oligomerization are presented.

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Regioselectively Modified Stereoregular Polysaccharides IX. A Synthetic Polysaccharide Having One Hydroxyl Group in Its Repeating Unit, 2,4-Dideoxy-(1→6)α-D-threo-hexopyranan

Cited by 8 publications

References 23 publications

Regioselectively Modified Stereoregular Polysaccharides X. Equilibrium Polymerization of 1,6-Anhydro-2-O-benzyl-3,4-dideoxy-β-D-threo-hexopyranose

Regioselectively Modified Stereoregular Polysaccharides X. Equilibrium Polymerization of 1,6-Anhydro-2-O-benzyl-3,4-dideoxy-β-D-threo-hexopyranose

Synthesis of a comb-shaped branched polysaccharide via ring-opening polymerization of a reactive anhydro disaccharide derivative

Unusual anionic desalting oligomerization of alkali metal salts of bromo-substituted bicyclic oxalactam

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