Synthesis of glycopolymers bearing mannaric pendants as inhibitors on the β‐glucuronidase activity: The inhibition mechanisms of mannaric‐ and glucaric‐compounds

A new styrene derivative having D ‐mannaric moiety, N‐p‐vinylbenzyl‐D ‐mannaramic acid (VB‐D ‐ManaH, 8 ) was synthesized though the ring‐opening reaction of D ‐mannaro‐1,4:6,3‐dilactone (D ‐MDL) with p‐vinylbenzylamine. VB‐D ‐ManaH was copolymerized with acrylamide (AAm) to give novel polymers having D ‐mannaric moiety in the pendants, P(VB‐D ‐ManaH‐co‐AAm), 10 . The resulting glycomonomer and polymer ( 8 and 10 ) bearing D ‐mannaric pendants were found to inhibit the β‐glucuronidase activity, although the inhibition ability of the corresponding saccharodilactone (D ‐MDL) was known to be low. Additionally, the inhibition ability of P(VB‐D ‐ManaH‐co‐AAm), 10 , was almost the same as that of the glycopolymer having D ‐glucaric pendants, P(VB‐6‐D ‐GlcaH‐co‐AAm), 1 , which was one of the most effective inhibitors for β‐glucuronidase, reported in our previous work. Thus, 10 and 8 may be the first D ‐mannaric strong inhibitors to the β‐glucuronidase activity. The Lineweaver–Burk plot suggested that the inhibition mechanisms of 10 and 8 were more complicated than in the case of the competitive and uncompetitive inhibition of N‐p‐(vinylbenzyl)‐6‐D ‐glucaramic ( 11 ) and N‐p‐(vinylbenzyl)‐1‐D ‐glucaramic acids ( 12 ), respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2032–2042, 2009     

Glycopolymeric inhibitors of β‐glucuronidase. III. Configurational effects of hydroxy groups in pendant glyco‐units in polymers upon inhibition of β‐glucuronidase

Two kinds of new glycopolymers, (P(VB‐1‐GlcaH‐co‐AAm), 9 ) and (P(VB‐1‐Glco‐co‐AAm), 10 ), were synthesized through the radical copolymerization of styrene derivatives bearing pendant D ‐glucaric and D ‐gluconic moieties, N‐(p‐vinylbenzyl)‐1‐D ‐glucaramide (VB‐1‐GlcaH, 7 ), and N‐(p‐vinylbenzyl)‐D ‐gluconamide (VB‐1‐Glco, 8 ), with acrylamide (AAm). Glycopolymer 9 bearing the pendant glucaric moiety at the first position inhibited the hydrolysis of a model compound for xenobiotics‐β‐glucuronide conjugates, p‐nitrophenyl β‐D ‐glucuronide, uncompetitively, in contrast to the competitive inhibition in the presence of the corresponding isomeric glycopolymer bearing the pendant D ‐glucaric unit at the sixth position (P(VB‐6‐GlcaH‐co‐AAm), 3 ) reported in our previous article. On the other hand, another copolymer 10 bearing the gluconic moiety was found not to inhibit the hydrolysis as well as the corresponding copolymer bearing pendant gulonic unit (P(VB‐6‐Glco‐co‐AAm), 4 ). These results indicate that the hydrolysis is influenced not only by existence of pendant carboxyl units but also by the direction on the linkage of the glyco‐units to the polymer frame. Therefore the configurational position of hydroxy groups in pendant glyco‐units in macromolecular inhibitors may be essential for the interaction with β‐glucuronidase. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4895–4903, 2006     

Imidazole‐initiated polymerizations of α‐amino acid N‐carboxyanhydrides – simultaneous chain‐growth and step‐growth polymerization

The N‐carboxyanhydrides (NCAs) of sarcosine (Sar), D ,L ‐leucine (D ,L ‐Leu), D ,L ‐phenylalanine (D ,L ‐Phe), and L ‐alanine (L ‐Ala) were polymerized in dioxane. Imidazole served as initiator and the NCA/initiator ratio was varied from 1/1 to 40/1. The isolated polypeptides were characterized by ¹H NMR spectroscopy, by MALDI‐TOF mass spectrometry, by viscosity measurements, and by SEC measurements in the case of poly(sarcosine). Cyclic oligopeptides were found in all reaction products and in the case of polySar, poly(D ,L ‐Leu), and poly(D ,L ‐Phe) the cycles were the main products. In the case of poly(L ‐Ala), rapid precipitation of β‐sheet lamellaes prevented efficient cyclizations and stabilized imidazolide endgroups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5690–5698, 2005     

Synthesis of optically active poly(amide‐imide)s derived from N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L‐leucine diacid chloride and aromatic diamines by microwave radiation

3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (4,4′‐carbonyldiphathalic anhydride) was reacted with L ‐leucine in a mixture of acetic acid and pyridine (3 : 2), and the resulting imide‐acid [N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L ‐leucine diacid] was obtained in quantitative yield. The compound was converted to the N,N′‐(4,4′‐carbonyldiphthaloyl)‐bis‐L ‐leucine diacid chloride by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride with several aromatic diamines such as 4,4′‐diaminodiphenyl methane, 2,4‐diaminotoluene, 4,4′‐sulfonyldianiline, p‐phenylenedi‐amine, 4,4′‐diaminodiphenylether, and m‐phenylenediamine was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as O‐cresol. The polymerization reactions proceeded rapidly compared with the conventional solution polycondensation and were completed within 6 min, producing a series of optically active poly(amide‐imide)s with a high yield and an inherent viscosity of 0.37–0.57 dL/g. All of the above polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of these optically active poly(amide‐imide)s are reported. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 177–186, 2001     

Proton transfer‐controlled anionic polymerization of methyl‐substituted β‐lactams with potassium t‐butoxide and subsequent coupling reaction with saccharides

The potassium t‐butoxide‐catalyzed ring‐opening polymerization of 3,3‐dimethyl‐ and 4,4‐dimethyl‐2‐azetidinone proceeds quantitatively in a mixture of N,N‐dimethylacetamide and 5–10 wt % of lithium chloride at 25°C to give the corresponding monodisperse polyamides. The addition of methyl α‐D ‐glucoside into the living polyamide system gives a novel polyamide linked with the glucose moiety at one chain end. A new graft copolymer composed of a water soluble polysaccharide (dextran) backbone and many monodisperse polyamide branches was also prepared by a similar coupling method. The difference in acidity among the lactam monomers, the corresponding polyamides, and the alcohols was essential for the attainment of such a proton transfer‐controlled system composed of the living polymerization and the subsequent coupling reaction. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 909–915, 1999     

Synthesis and polymerization of new styryl and methacryloyl monomers containing acidic saccharide moieties

New styryl‐type water‐insoluble and methacryloyl‐type water‐soluble monomers, N‐(p‐vinylbenzyl)‐1,2‐O‐isopropylidene‐6‐D ‐glucofuranuronamide and N‐(2‐methacryloylamino)ethyl‐1,2‐O‐isopropylidene‐6‐D ‐glucofuranuronamide, were synthesized from the most common acidic saccharide, D ‐glucuronic acid. Their radical homopolymerizations and copolymerizations with styrene and acrylamide were tried under various conditions. The isopropylidene groups in the resulting polymers were removed in a mixture of trifluoroacetic acid and water (2/1 v/v) to give the corresponding polymers with many pendant D ‐glucopyranuronyl groups with reactive reducing groups. The pendant reducing ends may be useful as potential binding sites under a hydrophilic atmosphere. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3893–3901, 2001     

Tertiary amine catalyzed polymerizations of α‐amino acid N‐carboxyanhydrides: The role of cyclization

Sarcosine N‐carboxyanhydride, D,L ‐alanine N‐carboxyanhydride, D,L ‐phenylalanine N‐carboxyanhydride, and D,L ‐leucine N‐carboxyanhydride were polymerized with pyridine or N‐ethyldiisopropylamine as the catalyst. With pyridine, cyclic oligo‐ and polypeptides were obtained in addition to water‐initiated or water‐terminated chains. The cyclopeptides were the main products in the case of sarcosine N‐carboxyanhydride and D,L ‐phenylalanine N‐carboxyanhydride. The fraction of cycles was particularly high when N‐methylpyrrolidone was used as the reaction medium. These results suggested the existence of a pyridine‐catalyzed zwitterionic mechanism. However, cyclopeptides were also obtained with N‐ethyldiisopropylamine as the catalyst. In this case, N‐deprotonation of N‐carboxyanhydrides, followed by the formation of N‐acyl N‐carboxyanhydride chain ends, was the most likely initiation mechanism. Various chain‐growth mechanisms were examined. In the case of γ‐benzyl ester‐L ‐glutamate N‐carboxyanhydride, side reactions such as the formation of pyroglutamoyl end groups were detected. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4680–4695, 2006     

Chemical synthesis of poly‐γ‐glutamic acid by polycondensation of γ‐glutamic acid dimer: Synthesis and reaction of poly‐γ‐glutamic acid methyl ester

α‐Methyl glutamic acid (L ‐L )‐, (L ‐D )‐, (D ‐L )‐, and (D ‐D )‐γ‐dimers were synthesized from L ‐ and D ‐glutamic acids, and the obtained dimers were subjected to polycondensation with 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and 1‐hydroxybenzotriazole hydrate as condensation reagents. Poly‐γ‐glutamic acid (γ‐PGA) methyl ester with the number‐average molecular weights of 5000∼20,000 were obtained by polycondensation in N,N‐dimethylformamide in 44∼91% yields. The polycondensation of (L ‐L )‐ and (D ‐D )‐dimers afforded the polymers with much larger |[α]_D | compared with the corresponding dimers. The polymer could be transformed into γ‐PGA by alkaline hydrolysis or transesterification into α‐benzyl ester followed by hydrogenation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 732–741, 2001     

Synthesis of polypeptides from activated urethane derivatives of α‐amino acids

A series of activated urethane‐type derivatives of α‐amino acids were synthesized and applied to polypeptide synthesis. The urethane used herein, N‐(4‐nitrophenoxycarbonyl)‐α‐amino acids 1 , were synthesized by N‐carbamoylation of γ‐benzyl‐L ‐glutamate, β‐benzyl‐L ‐aspartate, L ‐leucine, L ‐phenylalanine, and L ‐proline, with 4‐nitrophenyl chloroformate. When 1 was dissolved in N,N‐dimethylacetamide (DMAc) and heated at 60 °C, it was smoothly converted into the corresponding polypeptides with releasing 4‐nitrophenol and carbon dioxide. Spectroscopic analyses of the obtained polypeptides revealed that they were comparable with the authentic polypeptides synthesized by the ring‐opening polymerizations of amino acid N‐carboxyanhydrides (NCAs). Besides the successful polycondensations of a series of 1 , their polycondensations of 1a and other 1 were also successfully carried out to obtain the corresponding statistic copolypeptides. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2525–2535, 2008     

Dendron‐like poly(ε‐benzyloxycarbonyl‐L‐lysine)/linear PEO block copolymers: Synthesis,physical characterization,self‐assembly,and drug‐release behavior

Dendron‐like poly(ε‐benzyloxycarbonyl‐L ‐lysine)/linear poly(ethylene oxide) block copolymers (i.e., Dm‐PZLys‐b‐PEO, m = 0 and 3; Dm are the propargyl focal point poly(amido amine) dendrons having 2^m primary amine groups) were for the first time synthesized by combining ring‐opening polymerization (ROP) of ε‐benzyloxycarbonyl‐L ‐lysine N‐carboxyanhydride (Z‐Lys‐NCA) and click chemistry, where Dm‐PZLys homopolypeptides were click conjugated with azide‐terminated PEO. Their molecular structures and physical properties were characterized in detail by FTIR, ¹H NMR, gel permeation chromatography, differential scanning calorimetry, polarized optical microscopy, and wide angle X‐ray diffraction. Both homopolypeptides and copolymers presented a liquid crystalline phase transition for PZLys block, and the transition was irreversible. Moreover, the degree of crystallinity of PEO block within linear copolymers decreased from 96.2% to 20.4% with increasing PZLys composition, whereas that within dendritic copolymers decreased to zero. The secondary conformation of PZLys progressively changed from β‐sheet to α‐helix with increasing the chain length. These copolymers self‐assembled into spherical nanoparticles in aqueous solution, and the anticancer drug doxorubicin‐loaded nanoparticles gave a similar morphology compared with their blank counterparts. The drug‐loaded nanoparticles showed a triphasic drug‐release profile at aqueous pH 7.4 or 5.5 and 37 °C and sustained a longer drug‐release period for about 2 months. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and Conformational Analysis of 1′‐ and 3′‐Substituted 2‐Deoxy‐2‐fluoro‐D‐ribofuranosyl Nucleosides

Convergent syntheses of the 9‐(3‐X‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranosyl)adenines 5 (X=N₃) and 7 (X=NH₂), as well as of their respective α‐anomers 6 and 8 , are described, using methyl 2‐azido‐5‐O‐benzoyl‐2,3‐dideoxy‐2‐fluoro‐β‐D ‐ribofuranoside ( 4 ) as glycosylating agent. Methyl 5‐O‐benzoyl‐2,3‐dideoxy‐2,3‐difluoro‐β‐D ‐ribofuranoside ( 12 ) was prepared starting from two precursors, and coupled with silylated N⁶‐benzoyladenine to afford, after deprotection, 2′,3′‐dideoxy‐2′,3′‐difluoroadenosine ( 13 ). Condensation of 1‐O‐acetyl‐3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐β‐D ‐ribofuranose ( 14 ) with silylated N²‐palmitoylguanine gave, after chromatographic separation and deacylation, the N⁷‐β‐anomer 17 as the main product, along with 2′‐deoxy‐2′‐fluoroguanosine ( 15 ) and its N⁹‐α‐anomer 16 in a ratio of ca. 42 : 24 : 10. An in‐depth conformational analysis of a number of 2,3‐dideoxy‐2‐fluoro‐3‐X‐D ‐ribofuranosides (X=F, N₃, NH₂, H) as well as of purine and pyrimidine 2‐deoxy‐2‐fluoro‐D ‐ribofuranosyl nucleosides was performed using the PSEUROT (version 6.3) software in combination with NMR studies.     

Synthesis,conformation transition,liquid crystal phase,and self‐assembled morphology of thermosensitive homopolypeptide

Thermosensitive diethylene glycol‐derived poly(L ‐glutamate) homopolypeptides (i.e., poly‐L ‐EG₂‐Glu) with different molecular weights (MW) (M_n,GPC = 5380–32520) were synthesized via the ring‐opening polymerization (ROP) of EG₂‐L ‐glutamate N‐carboxyanhydride (EG₂‐Glu‐NCA) in N,N‐dimethylformamide solution at 50 °C. Their molecular structure, conformation transition, liquid crystal (LC) phase behavior, lower critical solution temperature (LCST) transition, and morphology evolution were thoroughly characterized by means of FTIR, ¹H NMR, gel permeation chromatography, differential scanning calorimetry, wide angle X‐ray diffraction, polarized optical microscope, transmission electron microscope, and dynamic light scattering. In solid state, the homopolypeptide poly‐L ‐EG₂‐Glu presented a conformation transition from α‐helix to β‐sheet with increasing their MW at room temperature, while it mainly assumed an α‐helix of 80–86% in aqueous solution. Poly‐L ‐EG₂‐Glu showed a thermotropic LC phase with a transition temperature of about 100 °C in solid state, while it gave a reversible LCST transition of 34–36 °C in aqueous solution. The amphiphilic homopolypeptide poly‐L ‐EG₂‐Glu self‐assembled into nanostructures in aqueous solution, and their critical aggregation concentrations decreased with increasing MW. Interestingly, their morphology changed from spherical micelles to worm‐like micelles, then to fiber micelles with increasing MW. This work provides a simple method for the generation of different nanostructures from a thermosensitive biodegradable homopolypeptide. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthetic polyhydroxypolyamides from galactaric,xylaric, D‐glucaric,and D‐mannaric acids and alkylenediamine monomers—some comparisons

The condensation polymerization in a methanol solution of four different esterified aldaric acids (D ‐glucaric, meso‐xylaric, meso‐galactaric, and D ‐mannaric) with even‐numbered alkylenediamines (C₂–C₁₂) gave polyhydroxypolyamides whose water solubilities and melting points were compared. In general, an increase in the alkylenediamine monomer length resulted in decreased polyamide water solubility. Differences in the polymer melting points and water solubilities were linked primarily to conformational differences of the monomer aldaryl units; for example, polyamides from meso‐galactaric acid with an extended zigzag conformation aldaryl monomer unit had higher melting points and lower water solubilities than those from D ‐glucaric and meso‐xylaric acids. The latter acid monomer units tended toward bent conformations that served to diminish intermolecular attractive forces between polymer chains, affecting polymer solubility and melting characteristics. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 594–603, 2000     

Chemoselective Synthesis of β‐Amino Ester or β‐Lactam via Sonochemical Reformatsky Reaction

A series of β‐amino esters were synthesized by the reaction of N‐tosyl aldimine or N‐hydroxy aldimine with bromoacetate by sonochemical Reformatsky reaction. The β‐N‐hydroxyamino ester was obtained and the formed sensitive hydroxylamino functionality was resistant under the reaction condition. The β‐lactam also was synthesized by the reaction of N‐p‐methoxy aldimine as reacting substrate under this sonochemical Reformatsky reaction condition.     

Polyol‐Metall‐Komplexe.47 Kristalline D‐Mannose‐Kupfer(II)‐Komplexe aus Fehlingscher Lösung

Polyol Metal Complexes.47¹⁾ Crystalline D ‐Mannose‐Copper Complexes from Fehling Solutions Blue, unstable crystals of K₃[Cu₅(β‐D ‐Manp)₄H_—13] · α‐D ‐Manp · 16.5 H₂O ( 1 ), which contain a pentanuclear cupric complex of the reducing sugar D ‐mannose in its β‐pyranose form (β‐D ‐Manp), have been obtained from ice‐cold aqueous alkaline solutions. The homoleptic pentacuprate contains bridging mannopyranose ligands, which are charged 4— and 2.5—. Addition of ethylenediamine (en) to such Fehling solutions yields N, N′‐Bis(β‐D ‐mannopyranosyl)‐ethylenediamine (L) as a condensation product of the diamine and mannopyranose. Crystals of [(en)₂Cu₇(β‐D ‐Manp1, 2, 3, 4H_—4)₂(L2, 3, 4H_—3)₂] · 26.6 H₂O ( 2 ) could be isolated. The heptanuclear cupric complex is a structural derivative of the homoleptic mannose complex.     

7‐Iodo‐5‐aza‐7‐deazaguanine: Syntheses of Anomeric D‐ and L‐Configured 2‐Deoxyribonucleosides

Iodination of N²‐isobutyryl‐5‐aza‐7‐deazaguanine ( 7 ) with N‐iodosuccinimide (NIS) gave 7‐iodo‐N²‐isobutyryl‐5‐aza‐7‐deazaguanine ( 8 ) in a regioselective reaction (Scheme 1). Nucleobase‐anion glycosylation of 8 with 2‐deoxy‐3,5‐di‐O‐toluoyl‐α‐D ‐ or α‐L ‐erythro‐pentofuranosyl chloride furnished anomeric mixtures of D ‐ and L ‐nucleosides. The anomeric D ‐nucleosides were separated by crystallization to give the α‐D ‐anomer and β‐D ‐anomer with excellent optical purity. Deprotection gave the 7‐iodo‐5‐aza‐7‐deazaguanine 2′‐deoxyribonucleosides 3 (β‐D ; ≥99% de) and 4 (α‐D ; ≥99% de). The reaction sequence performed with the D ‐series was also applied to L ‐nucleosides to furnish compounds 5 (β‐L ; ≥99% de) and 6 (α‐L ; ≥95% de).     

Synthesis and radical polymerization behavior of bifunctional vinyl monomer derived from N‐vinylacetamide and p‐chloromethylstyrene

The radical polymerization of N‐(p‐vinylbenzyl)‐N‐vinylacetamide ( 1 ) prepared by the reaction of N‐vinylacetamide with p‐chloromethylstyrene was carried out by using radical initiators such as AIBN or BPO in benzene, chlorobenzene, or bulk. As a result, poly 1 was successfully isolated by dialysis (yield, 10–36%). The crosslinking reaction of poly 1 was carried out at 60–100 °C for 8 h. By using a radical initiator such as AIBN or BPO (3 mol %), the crosslinking reaction proceeded (yield, 63–79%). Moreover, the crosslinking reaction of poly 1 proceeded at 100 °C without a radical initiator in 50% yield. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2714–2723, 2006     

Nitrosation of Sugar Oximes: Preparation of 2‐Glycosyl‐1‐hydroxydiazene‐2‐oxides

Oximes of glucose, xylose, lactose, fructose, and mannose have been prepared. Nitrosation of the oximes of glucose, xylose, and lactose with NaNO₂/HCl afforded 2‐(β‐glycopyranosyl)‐1‐hydroxydiazene‐2‐oxides, which were isolated as salts 13 , 22 , and 28 . Nitrosation of fructose oxime 29 furnished fructose, whereas nitrosation of mannose oxime 30 with NaNO₂/HCl afforded the 1‐hydroxy‐2‐(β‐d‐ mannopyranosyl)diazene‐2‐oxide 32 , from which the p‐anisidinium salt 31 and the sodium salt 33 were prepared. However, nitrosation of 30 with isopentyl nitrite in aqueous solutions of CsOH or KOH resulted in the formation of the 2‐(α‐D ‐mannofuranosyl)‐1‐hydroxydiazene‐2‐oxide salts 34 and 35 , respectively. Methylation of the ammonium 2‐(β‐D ‐glucopyranosyl)‐1‐hydroxydiazene‐2‐oxide 13 yielded the 1‐methoxy compound, which was benzoylated to afford the tetra‐O‐benzoate 14 a , the structure of which was confirmed by X‐ray diffraction analysis. From the glucose O‐methyloximes 15 and 16 the N‐methoxy‐N‐nitroso‐2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranosylamine 18 was prepared. The structure of this compound was confirmed by X‐ray diffraction analysis. Treatment of acetobromoglucose with cupferron furnished the 1‐(2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranosyloxy)‐2‐phenyldiazene‐2‐oxide 20 .     

Tuning the parameters of the suspension polymerization of styrene,divinylbenzene, and N‐(p‐vinylbenzyl)‐ 4,4‐dimethylazlactone

Azlactone‐functionalized microporous polystyrene resins were synthesized by suspension polymerization of styrene, divinylbenzene and N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone (VBM). A fractional factorial design of experiments (DOE) has been used to evaluate the influence of several parameters (factors) on the physical and chemical properties (responses) of the resins. Six factors were considered: (i) the organic/aqueous phase ratio, (ii) the amount of the functional monomer N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone, (iii) the amount of stabilizer, (iv) the amount of initiator, (v) the stirring speed, and (vi) the equilibration time. The process responses were the yield of polymerization, the diameter of the beads and their polydispersity, their swelling ratio in dichloromethane and the accessibility ratio of the immobilized azlactone sites. This methodology enables the determination of an optimal combination of the six factors to synthesize beads in high yield (92%) with remarkable properties for SPOS applications (azlactone sites loading = 1.57 mmol/g, swelling ratio in dichloromethane = 5.0 mL/g and 100% accessibility ratio). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3677–3686, 2007     

Synthesis of a new 2‐amino‐glycan,poly‐(1→6)‐α‐D‐mannosamine,by ring‐opening polymerization of 1,6‐anhydro‐mannosamine derivatives

A stereoregular 2‐amino‐glycan composed of a mannosamine residue was prepared by ring‐opening polymerization of anhydro sugars. Two different monomers, 1,6‐anhydro‐2‐azido‐mannose derivative ( 3 ) and 1,6‐anhydro‐2‐(N, N‐dibenzylamino)‐mannose derivative ( 6 ), were synthesized and polymerized. Although 3 gave merely oligomers, 6 was promptly polymerized into high polymers of the number‐average molecular weight (M_n) of 2.3 × 10⁴ to 2.9 × 10⁴ with 1,6‐α stereoregularity. The differences of polymerizability of 3 and 6 from those of the corresponding glucose homologs were discussed. It was found that an N‐benzyl group is exceedingly suitable for protecting an amino group in the polymerization of anhydro sugars of a mannosamine type. The simultaneous removal of O‐ and N‐benzyl groups of the resulting polymers was achieved by using sodium in liquid ammonia to produce the first 2‐amino‐glycan, poly‐(1→6)‐α‐D ‐mannosamine, having high molecular weight through ring‐opening polymerization of anhydro sugars.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012