Synthesis of the two monomethyl esters of the disaccharide 4-O-alpha-D-galacturonosyl-D-galacturonic acid and of precursors for the preparation of higher oligomers methyl uronated in definite sequences.

Methyl (alpha-D-galactopyranosyluronic acid)-(1-->4)-D-galactopyranuronate and methyl alpha-D-galactopyranosyl-uronate-(1-->4)-D-galactopyranuronic acid have been synthesized by coupling methyl (benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate (3) or benzyl (benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate (4) with benzyl (phenyl 2,3,4-tri-O-benzyl-1-thio-beta-D-galactopyranosid)uronate and methyl (phenyl 2,3,4-tri-O-benzyl-1-thio-beta-D-galactopyranosid)uronate, respectively, using N-iodosuccinimide and trifluoromethanesulphonic acid as promoters, followed by removal of the benzyl groups. The 4'-OH unprotected dimers benzyl (methyl 2,3-di-O-benzyl-alpha-D-galactopyranosyluronate)-(1-->4)-(benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate and methyl (benzyl 2,3-di-O-benzyl-alpha-D-galactopyranosyluronate)-(1-->4)-(benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate were prepared from methyl (phenyl 2,3-di-O-benzyl-1-thio-4-O-trimethylsilyl-beta-D-galactopyranosid) uronate and benzyl (phenyl 2,3-di-O-benzyl-1-thio-4-O-trimethylsilyl-beta-D-galactopyranosid) uronate and acceptors 4 or 3, respectively. These compounds have been designed to serve as precursors for the preparation of higher-membered D-galacturonic acid oligomers methyl esterified in definite positions.     

Formation of lipoxin B by the pure reticulocyte lipoxygenase via sequential oxygenation of the substrate

The pure reticulocyte lipoxygenase converts 15LS-hydroxy-5,8,11,13(Z,Z,Z,E)-icosatetraenoic acid (15LS-HETE) methyl ester to a complex mixture of products containing 5DS,14LR,15LS-trihydro(pero)xy-6E,++ +8Z,10E,12E-icosatetraenoate methyl ester (lipoxin B methyl ester), 5DS,15LS-DiH(P)ETE methyl ester and four 8,15LS-DiH(P)ETE methyl ester isomers [DiH(P)ETE = dihydro(pero)xy-icosatetraenoic acid]. After a short incubation period (15 min) 5DS,15LS-DiH(P)ETE methyl ester was found to be the main product, whereas after a 3-h incubation lipoxin B methyl ester was the predominant product. The reaction shows a remarkable stereoselectivity since only small amounts of other trihydroxy tetraenes are formed. Anaerobiosis, heat inactivation of the enzyme, or incubation in the presence of lipoxygenase inhibitors (icosatetraynoic acid, nordihydroguaiaretic acid) completely abolished the reaction. The complete steric structure of the major tetraene product (lipoxin B methyl ester) was established by ultraviolet spectroscopy, HPLC on four different types of columns, gas chromatography/mass spectrometry, gas/liquid chromatography of the ozonolysis fragments of the menthoxycarbonyl derivatives, and by 400-MHz 1H-NMR. Atmospheric oxygen was incorporated at carbon-5 and carbon-14 into the major product. 5DS,15LS-DiH(P)ETE methyl ester was shown to be an intermediate in the synthesis. Lipoxin B was also formed during the oxygenation of arachidonic acid, 15LS-HETE and 5DS,15LS-DiHETE. The results presented here indicate that lipoxin B can be formed by pure lipoxygenases via a sequential oxygenation of arachidonic acid or its hydro(pero)xy derivatives.     

Characterisation and X-ray crystallography of products from the Bucherer-Bergs reaction of methyl 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside

Methyl 2,3-O-isopropylidene-alpha-D-mannofuranosidurononitrile [alternative name: methyl (5R)-5-C-cyano-2,3-O-isopropylidene-alpha-D-lyxofuranoside] (2), methyl 2,3-O-isopropylidene-alpha-D-mannofuranosiduronamide [methyl (5S)-5-C-carbamoyl-2,3-O-isopropylidene-alpha-D-lyxofuranoside; methyl (5S)-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosiduronamide] (3), methyl 2,3-O-isopropylidene-alpha-D-mannofuranosiduronic acid [methyl (5S)-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosiduronic acid] (4), methyl 5-deoxy-2,3-O-isopropylidene-5-ureido-beta-L-gulofuranosiduronamide [methyl (5R)-5-deoxy-2,3-O-isopropylidene-5-ureido-alpha-D-lyxo-hexofuranosiduronamide (5), and (4S,5S,6R)-5,6-dihydro-6-hydroxy-4,5-isopropylidenedioxy-4H-pyrido[2,1-e]imidazolidine-2',4'-dione [IUPAC name: (3aS,4R,8aS)-4-hydroxy-2,2-dimethyl-3a,8a-dihydro-4H-1,3-dioxa-4a,6-diaza-s-indacene-5,7-dione] (6), instead of the expected hydantoin derivative, were obtained from the Bucherer-Bergs reaction of methyl 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside (1). The structure of 6 was deduced from NMR and mass spectral data and confirmed by X-ray crystallography. The configuration at C-5 in 2-5 was confirmed by establishing the 5S configuration of 3 by X-ray crystallography. Conformations of the six- and five-membered rings in 3 and 6 are also discussed.     

Stereochemical studies of the C-methylation of deoxycytidine catalyzed by HhaI methylase and the N-methylation of deoxyadenosine catalyzed by EcoRI methylase

The steric course of methyl group transfer catalyzed by two DNA methylases, HhaI methylase, a DNA (cytosine-5)-methyltransferase, and EcoRI methylase, which methylates at N6 of adenosine, has been studied with (methyl-R)- and (methyl-S)-[methyl-2H1,3H]adenosylmethionine as the methyl donor, using as substrates poly-d(GC) (HhaI) and the dodecamer oligonucleotide duplex d(CGCGAATTCGCG) (EcoRI), respectively. The methylated nucleotides were degraded to convert the chiral methyl groups into acetic acid for configurational analysis. It was found that both enzymatic reactions proceed with inversion of configuration of the methyl group.     

Synthesis of methyl pyranosides and furanosides of 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) by acid-catalysed solvolysis of the acetylated derivatives

Treatment of methyl 2,4,5,7,8-penta-O-acetyl-3-deoxy-alpha-D-manno-oct- 2-ulopyranosonic acid, or its methyl ester, with refluxing methanolic 0.1 M hydrogen chloride for 16 h gave 95% of methyl (methyl 3-deoxy-alpha-D-manno-oct-2-ulopyranosid)onate. Acetylation of the methyl ester of 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) gave mainly methyl 2,4,6,7,8-penta-O-acetyl-3-deoxy-alpha,beta-D-manno-oct-2-ulofuranoso nate. Treatment of this mixture with methanolic 0.02 M hydrogen chloride at room temperature gave methyl (methyl 3-deoxy-alpha, beta-D-manno-oct-2-ulofuranosid)onate and the corresponding 4-acetates which were isolated by reverse-phase column chromatography of their 7,8-O-isopropylidene derivatives. Confirmation of the position of the isopropylidene group was obtained by acetylation to give methyl (methyl 4,6-di-O-acetyl-3-deoxy-7,8-O-isopropylidene-alpha,beta-D-manno-oct-2-ul ofuranosid)onate. The furanose anomers were differentiated primarily by J3,4 values (alpha approximately 6.1 Hz, beta approximately 2.2 Hz). The anomeric configuration in the furanose series has been assigned on the basis of optical rotation.     

藏红花花瓣和雄蕊挥发油化学成分GC-MS分析及比较

采用水蒸气蒸馏法从藏红花花瓣和雄蕊中提取挥发油,用GC-MS技术结合计算机检索对其二者化学成分进行分离和鉴定,用色谱峰面积归一化法计算各组分的相对含量.花瓣中共鉴定出16种化合物,主要成分为正二十六烷(11.60％)、正十五烷(11.31％)、棕榈酸甲酯(10.82％)、油酸甲酯(10.35％)、2,4-二叔丁基苯酚(9.63％)、亚油酸甲酯(7.18％)、藏红花醛(5.66％);雄蕊中共鉴定出20种化合物,主要成分为油酸甲酯(30.83％)、亚油酸甲酯(24.12％)、环已醇(16.80％)、硬脂酸甲酯(12.88％)、棕榈酸甲酯(8.97％)、花生酸甲酯(1.18％)、苯并噻唑(1.01％).     

Further definition of the size of the blood group-i antigenic determinant using a chemically synthesised octasaccharide of poly-N-acetyllactosamine type.

In earlier studies, the minimum structure which inhibited the binding of anti-i to an i-active glycoprotein was the linear trisaccharide, beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)-D-Gal. There was an increasing hierarchy of inhibitory activities in the linear tetrasaccharide, beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-beta-D -GlcNAc , its methyl beta-glycoside, and in the methyl beta-glycoside of the hexasaccharide. The linear octasaccharide methyl beta-glycoside in this series is approximately only half as active as the hexasaccharide methyl beta-glycoside. Analyses by high resolution 1H-n.m.r. of these two oligosaccharides indicated that they have similar conformations in solution, and there is no evidence for the occurrence of inter-molecular interactions which might partially hinder the binding of anti-i to the octasaccharide methyl beta-glycoside. These results are consistent with the size of the i antigen being in the region of a hexasaccharide. It is proposed that the methyl aglycon group of the hexasaccharide methyl beta-glycoside confers an above normal activity by presenting a hydrophobic area for additional contact in the vicinity of the antibody-combining site.     

Volatile Methyl Esters of Medium Chain Length from the Bacterium Chitinophaga Fx7914

The analysis of the volatiles released by the novel bacterial isolate Chitinophaga Fx7914 revealed the presence of ca. 200 compounds including different methyl esters. These esters comprise monomethyl‐ and dimethyl‐branched, saturated, and unsaturated fatty acid methyl esters that have not been described as bacterial volatiles before. More than 30 esters of medium C‐chain length were identified, which belong to five main classes, methyl (S)‐2‐methylalkanoates (class A), methyl (S)‐2,(ω?1)‐dimethylalkanoates (class B), methyl 2,(ω?2)‐dimethylalkanoates (class C), methyl (E)‐2‐methylalk‐2‐enoates (class D), and methyl (E)‐2,(ω?1)‐dimethylalk‐2‐enoates (class E). The structures of the compounds were verified by GC/MS analysis and synthesis of the target compounds as methyl (S)‐2‐methyloctanoate ( 28 ), methyl (S)‐2,7‐dimethyloctanoate ((S)‐ 43 ), methyl 2,6‐dimethyloctanoate ( 49 ), methyl (E)‐2‐methylnon‐2‐enoate ( 20a ), and methyl (E)‐2,7‐dimethyloct‐2‐enoate ( 41a ). Furthermore, the natural saturated 2‐methyl‐branched methyl esters showed (S)‐configuration as confirmed by GC/MS experiments using chiral phases. Additionally, the biosynthetic pathway leading to the methyl esters was investigated by feeding experiments with labeled precursors. The Me group at C(2) is introduced by propanoate incorporation, while the methyl ester is formed from the respective carboxylic acid by a methyltransferase using S‐adenosylmethionine (SAM).     

Stereochemical course of the methylation of the polygalacturonic acid carboxyl groups of pectin

The steric course of the methyl group transfer to polygalacturonic acid to form the methyl ester group in pectin was studied using S-adenosylmethionine (AdoMet) carrying a methyl group made chiral by labeling with ¹H, ²H, ³H, in an asymmetric arrangement. The incubation of the two diastereomers of this substrate with a particulate enzyme preparation obtained from Phaseolus aureus (mung bean) shoots gave the corresponding pectins. These were degraded in a series of stereochemically unambiguous reactions that converted the methoxy group into the methyl group of acetate, which was then analyzed for its configuration. The results indicate that the transfer of the methyl group from the sulfur of AdoMet to the oxygen of the carboxyl group proceeds with inversion of configuration of the methyl group.     

Synthesis of methyl 6'-deoxy-6'-fluoro-alpha-isomaltoside and of the corresponding trisaccharide

Methyl 6-O-(6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl)-2,3,4-tri- O-benzyl-alpha-D-glucopyranoside (5) was formed with high stereoselectivity when the condensation of methyl 2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl (1) with 6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl chloride in ether was promoted with silver perchlorate in the presence of 2,4,6-trimethylpyridine. O-Deacetylation of 5, followed by treatment of the formed 6, containing only HO-6' unsubstituted, with diethylaminosulfur trifluoride (DAST) or dimethylaminosulfur trifluoride (methyl DAST) gave the per-O-benzyl derivative (9) of methyl 6'-deoxy-6'-fluoro-alpha-isomaltoside. Compound 9 was also obtained by condensation of 1 with 2,3,4-tri-O-benzyl-6-deoxy-6-fluoro-beta-D-glucopyranosyl fluoride (4) in the presence of silver perchlorate and anhydrous stannous chloride. The fully benzylated methyl alpha-glycoside (15) of 6-deoxy-6-fluoro-isomaltotriose, was obtained by condensation of 6 with 4. Hydrogenolysis of 9 and 15 gave the methyl alpha-glycosides of isomaltose and isomaltotriose fluorinated at C-6 of their (nonreducing) D-glucosyl group. Fluoride-ion displacements involving DAST and methyl DAST gave practically identical results, but mixtures arising from reactions involving the latter reagent were lighter-colored and easier to resolve by chromatography. The isolation of methyl alpha-glycosides of 6'-deoxy-6'-fluorogentiobiose and of 6'-O-(6-deoxy-6-fluoro-beta-D-glucopyranosyl) isomaltose is also described.     

A (13)C NMR study on the interactions of calcium chloride/potassium chloride with pyranosides in D(2)O

The (13)C NMR spectra of methyl beta-d-glucopyranoside, methyl beta-d-galactopyranoside, methyl beta-d-xylopyranoside, and methyl beta-l-arabinopyranoside were recorded in CaCl(2)/KCl+D(2)O mixtures and in D(2)O. The chemical shifts of C-1, C-3, and C-5 in the methyl beta-d-glucopyranoside and methyl beta-d-galactopyranoside decrease rapidly as molalities of CaCl(2)/KCl increase, while those of C-1, C-2, and C-3 in the methyl beta-d-xylopyranoside and methyl beta-l-arabinopyranoside decrease rapidly as molalities of CaCl(2)/KCl increase. Cations (Ca(2+)/K(+)) can weakly complex with O in OMe of the pyranosides studied. Results are discussed in terms of the stereochemistry of the pyranoside molecules and the structural properties of the ions.     

Individual assignments of the methyl resonances in the 1H nuclear magnetic resonance spectrum of the basic pancreatic trypsin inhibitor.

In earlier work the resonances of the 20 methyl groups in the basic pancreatic trypsin inhibitor (BPTI) had been identified in the 360-MHz 1H nuclear magnetic resonance (NMR) spectra and most of the methyl lines had from spin-decoupling experiments been assigned to the different types of amino acid residues. The assignments to the different amino acid types were now completed by studies of the saturation transfer between the denatured and the globular forms of the inhibitor and by spin-decoupling experiments in nuclear Overhauser enhancement (NOE) difference spectra. These distinguished between the methyl resonances of Ala and Thr. Furthermore, for most of the methyl resonances, individual assignments to specific residues in the amino acid sequence were obtained from measurements of intramolecular proton-proton NOE's, use of lanthanide NMR shift and relaxation probes, and comparative studies of various chemically modified forms of BPTI. These data provide the basis for individual assignments of the methyl 13C NMR lines in BPTI and for detailed investigations of the relations between the spatial structure of the protein and the chemical shifts of the methyl groups. The methyl groups in BPTI are of particular interest since they are located almost exclusively on the surface of the protein and thus represent potential natural NMR probes for studies of the protein-protein interactions in the complexes formed between BPTI and a variety of proteases.     

On the mechanism of action of methyl chymotrypsin

The properties of a-chymotrypsin methylated at histidine-57 were examined to explain the mechanism of this enzyme which is about 10⁵ times less active than chymotrypsin. Studies on the protein showed (i) an alteration in the acyl and leaving group specificity, (ii) decreased binding of some protein protease inhibitors by methyl chymotrypsin, (iii) lack of dimerization of methyl chymotrypsin at low pH, (iv) decreased stability of methyl chymotrypsin in urea, (v) a larger solvent deuterium isotope effect with methyl chymotrypsin, and (vi) decreased binding of a tetrahedral intermediate analog to methyl chymotrypsin. These properties suggest that while only subtle alterations occur in the active site upon methylation of His-57, the transition state and the tetrahedral intermediate are destabilized but not to the same extent. General base catalysis remains an integral feature of the hydrolytic mechanism of the modified chymotrypsin, and the base appears to be the methylated nitrogen of the imidazole moiety of His-57.     

Novel 4-thiogalactofuranosyl-containing disaccharides with nitrogen in the interglycosidic linkage

The syntheses of three novel disaccharides containing a 4-thiogalactofuranosyl residue as the non-reducing unit and a nitrogen in the interglycosidic linkage are described. Acid-catalyzed condensation reactions of 4-thio-alpha/beta-D-galactofuranose with either methyl 3-amino-3-deoxy-alpha-D-mannopyranoside, methyl 2-amino-2-deoxy-alpha-D-mannopyranoside, or methyl 2-acetamido-6-amino-2,6-dideoxy-beta-D-glucopyranoside gave methyl 3-amino-3-deoxy-3-N-(4-thio-alpha/beta-D-galactofuranosyl)-alpha-D-manno pyranoside, methyl 2-amino-2-deoxy-2-N-(4-thio-alpha/beta-D-galactofuranosyl)-alpha-D-manno pyranoside, or methyl 2-acetamido-6-amino-2,6-dideoxy-6-N-(4-thio-alpha/beta-D-galactofuranosy l)-beta-D-glucopyranoside.     

金线莲挥发油化学成分的研究

采用水蒸气蒸馏法提取花叶开唇兰挥发油,用GC毛细管柱进行分析,归一化法测定其相对含量,并用GC-MS法鉴定化学成分。检出182个成分,鉴定出73个化合物,占挥发油总量的92.64%,主要成分为:正十六烷酸(25.22%)、(Z,Z)-9,12-十八碳二烯酸甲酯(6.47%)、11,14,17-二十碳三烯酸甲酯(4.42%)、(Z,Z)-9,12-十八碳二烯酸(15.35%)和(Z,Z,Z)-9,12,15-十八碳三烯酸甲酯(13.64%)。     

Fatty acids,part 5: A study of the oxymercuration-demercuration reaction of some C11-unsaturated fatty esters and methyl octadec-cis-10-en-5-ynoate

The methoxymercuration-demercuration reactions of all the methyl cis-undecenoates are reported. Oxymercuration reaction of acetylenic esters gives keto- and hydroxy-esters when demercurated with hydrochloric acid and sodium borohydride respectively. Similar reactions are carried out with methyl octadec-cis-10-en-5-ynoate, which give the methyl 5(6)-oxooctadec-cis-10-enoate and 5(6)-hydroxy-10(11)-methoxyoctadecanoate isomers.Reduction of the methyl 5(6)-oxooctadec-cis-10-enoates with sodium borohydride yields the corresponding methyl hydroxy-esters, which on treatment with mercuric acetate (in methanol) and demercurated with sodium borohydride give methyl 5-hydroxy-10(11)-methoxyocta-decanoates and the 2,6-disubstituted tetrahydropyranyl derivative, methyl 6,10-epoxyoctadecanoate.     

Oxidation of methyl halides by the facultative methylotroph strain IMB-1.

Washed cell suspensions of the facultative methylotroph strain IMB-1 grown on methyl bromide (MeBr) were able to consume methyl chloride (MeCl) and methyl iodide (MeI) as well as MeBr. Consumption of >100 microM MeBr by cells grown on glucose, acetate, or monomethylamine required induction. Induction was inhibited by chloramphenicol. However, cells had a constitutive ability to consume low concentrations (<20 nM) of MeBr. Glucose-grown cells were able to readily oxidize [(14)C]formaldehyde to (14)CO(2) but had only a small capacity for oxidation of [(14)C]methanol. Preincubation of cells with MeBr did not affect either activity, but MeBr-induced cells had a greater capacity for [(14)C]MeBr oxidation than did cells without preincubation. Consumption of MeBr was inhibited by MeI, and MeCl consumption was inhibited by MeBr. No inhibition of MeBr consumption occurred with methyl fluoride, propyl iodide, dibromomethane, dichloromethane, or difluoromethane, and in addition cells did not oxidize any of these compounds. Cells displayed Michaelis-Menten kinetics for the various methyl halides, with apparent K(s) values of 190, 280, and 6,100 nM for MeBr, MeI, and MeCl, respectively. These results suggest the presence of a single oxidation enzyme system specific for methyl halides (other than methyl fluoride) which runs through formaldehyde to CO(2). The ease of induction of methyl halide oxidation in strain IMB-1 should facilitate its mass culture for the purpose of reducing MeBr emissions to the atmosphere from fumigated soils.     

Syntheses of the methyl glycosides of the repeating units of chondroitin 4- and 6-sulfate

3,4,6-Tri-O-acetyl-D-galactal was transformed into methyl 6-O-acetyl-2-azido-4-O-benzyl-2-deoxy-beta-D-galactopyranoside and its 4-O-acetyl-6-O-benzyl analogue, each of which was glycosylated with activated, O-acetylated derivatives of methyl D-glucopyranosyluronate. The resulting beta-(1----3)-linked disaccharide derivatives were each reductively N-acetylated, hydrogenolysed, O-sulfated, and saponified to afford the disodium salts of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside and the 6-O-sulfo analogue. D-Galactal was also transformed into activated derivatives of 2-azido-3,6-di-O-benzyl-2-deoxy-D-galactopyranose and their 3,4-di-O-benzyl analogues with various substituents at O-4 and O-6. These glycosyl donors were condensed with 6-O-protected derivatives of methyl 2,3-di-O-benzyl-beta-D-glucopyranoside to give the beta-(1----4)-linked disaccharide derivatives, which were selectively deprotected, then oxidised at C-6 of the gluco unit, reductively N-acetylated, selectively deprotected, O-sulfated at C-4 or C-6 of the galacto unit, and hydrogenolysed to give the disodium salts of methyl 4-O-(2-acetamido-2-deoxy-4-O-sulfo-beta-D-galactopyranosyl)-beta-D- glucopyranosiduronic acid and the 6-O-sulfo analogue.     

Block copolymerization of α-amino acid N-carboxyanhydride initiated by vinyl polymers having a terminal amino group and the characterization of the block copolymers

Poly(methyl methacrylate) and polystyrene having terminal amino groups were synthesized by the radical polymerization of those monomers in the presence of 2-mercaptoethylammonium chloride as a chain-transfer agent. By the terminal group analysis and the molecular weight determination of the polymers, 0.5–1.3 amino groups were found in a chain of poly(methyl methacrylate) and 0.5–2.5 amino groups in a chain of polystyrene. Using these polymers having a terminal amino group as an initiator, the block polymerization of α-amino acid N-carboxyanhydride (NCA) was carried out. In the polymerizations of Glu(OBzl) NCA and Lys(Z) NCA by the poly(methyl methacrylate) initiator, the terminal amino group underwent a nucleophilic addition reaction to NCA and initiated the polymerization, yielding A-B-type block copolymers in a high yield. The same was observed in the polymerizations of Gly(OBzl) NCA and Lys(Z) NCA by the polystyrene initiator. By eliminating the protecting groups of the side chains of the polypeptide segment, the block copolymers poly(methyl methacrylate)-poly(Glu), poly(methyl methacrylate)-poly(Lys), polystyrene-poly(Glu) and polystyrene-poly(Lys) were synthesized with little side reactions. The side chain amino groups of poly(Lys) segment in the poly(methyl methacrylate)-poly(Lys) block copolymers were sulphonated or stearoylated successfully.     

Synthesis of some D-mannosyl-oligosaccharides containing the methyl and 4-nitrophenyl beta-D-mannopyranoside units

Methyl 3,4,6-tri-O-benzyl-beta-D-mannopyranoside (2), methyl 2,3-O-isopropylidene-beta-D-mannopyranoside (11), and 4-nitrophenyl 2,3-O-isopropylidene-beta-D-mannopyranoside (12) were each condensed with 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl bromide (1) in the presence of mercuric cyanide, to give after deprotection, methyl 2-(5) and 6-O-alpha-D-mannopyranosyl-beta-D-mannopyranoside (15), and 4-nitrophenyl 6-O-alpha-D-mannopyranosyl-beta-D-mannopyranoside (20), respectively. A similar condensation of 11 with 3,4,6-tri-O-acetyl-2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-a lpha-D- mannopyranosyl bromide (21) and 2,3,4-tri-O-acetyl-6-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-a lpha D-mannopyranosyl bromide (25), followed by removal of protecting groups, afforded methyl O-alpha-D-mannopyranosyl-(1----2)-O-alpha-D-mannopyranosyl-(1----6)-beta -D- mannopyranoside (24) and methyl O-alpha-D-mannopyranosyl-(1----6)-O-alpha-D-mannopyranosyl-(1----6)-beta -D- mannopyranoside (28), respectively. Bromide 25 was also condensed with 12 to give a trisaccharide derivative which was deprotected to furnish 4-nitrophenyl O-alpha-D-mannopyranosyl-(1----6)-alpha-D-mannopyranosyl-(1----6)-beta-D - mannopyranoside (31). Phosphorylation of methyl 3,4,6-tri-O-benzyl-2-O-alpha-D-mannopyranosyl-beta-D-mannopyranoside and 15 with diphenyl phosphorochloridate in pyridine gave the 6'-phosphates 6 and 16, respectively. Hydrogenolysis of the benzyl and phenyl groups provided methyl 2-O-(disodium alpha-D-mannopyranosyl 6-phosphate)-beta-D-mannopyranoside (7) and methyl 6-O-(disodium alpha-D-mannopyranosyl 6-phosphate)-beta-D-mannopyranoside (17) after treatment with Amberlite IR-120 (Na+) cation-exchange resin. The structures of compounds 5, 7, 15, 17, 20, 24, 28, and 31 were established by 13C-n.m.r. spectroscopy.