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A hot water extract of Sasa veitchii is a health-promoting food in general use. To analyze the structure and function of the polysaccharide fraction of the extract, a macromolecular fraction was obtained by dialysis (HMF) and two polysaccharide fractions (NPS and APS) were separated by DEAE-Sephadex chromatography. HMF strongly reacted with human sera and immunoglobulin preparations. All of the IgM, IgG, and IgA classes of antibodies were reacted with HMF. Comparing the reactivity of NPS and APS, NPS showed significantly stronger reactivity to the sera. From physicochemical analysis, their molecular weights are 20,000 and 8,000, respectively. Sugar analyses of the acid hydrolysates indicated rhamnose, arabinose, xylose, mannose, glucose, and galactose in the molar ratio of 1.0 : 2.3 : 1.5 : 3.8 : 0.6 : 5.3 for NPS and 1.0 : 3.0 : 2.6 : 0.8 : 6.3 : 3.0 for APS, and suggested major differences in the ratio of hexoses. APS also contained 2.6% galacturonic acid. Methylation analyses suggested that 1) both NPS and APS have a highly branched structure, 2) only NPS contains galactofuranose residue at the non-reducing terminal. Partial acid hydrolysis of HMF and subsequent dialysis recovered a high molecular weight fraction, but the resulting product had significantly low immunochemical reactivity. Considering the physicochemical and immunochemical analyses, the major epitope structure of NPS was suggested to be galactofuranose residues. Immunochemical reactivity of the polysaccharide is a key molecular mechanism for the health promoting activity of S. veitchii.

Partial acid hydrolysis of a new water-absorbing polysaccharide (WAP) from the family Oxalobacteraceae gave six di-, four tri-, two tetra-, two penta-, and one hexasaccharides composed of mannose, glucose, and/or galactose. The structures of oligosaccharides 1-15 were elucidated by extensive 2D NMR spectroscopic analyses. (1)H- and (13)C-NMR chemical shift assignments of oligosaccharides 1-14 are presented.

The chemical structure of a new water-absorbing polysaccharide (WAP), which was isolated from a liquid culture of bacterium belonging to the family Oxalobacteraceae, was analyzed by fragmentation analysis and methylation techniques. Mild acid hydrolysis of WAP gave six di-, four tri-, two tetra-, two penta-, and one hexasaccharides composed of mannose, glucose and/or galactose. These structures were elucidated by extensive 2D NMR spectroscopic analyses. The structure of the WAP has been proposed to have a new heptasaccharide as a repeating unit, →4)-β-D-Glcp-(1→4)-β-D-Manp-(1→4)-β-D-Glcp-(1→4)-[β-D-Galp-(1→3)-β-D-Glcp-(1→3)-β-D-Galp-(1→3)]-β-D-Galp-(1→.

It was shown that 6-dimethoxymethyl-1,2-dihydro-2-oxo-3-pyridinecarbonitrile (5) is easily convertible into the titled ring system by a stepwise method. Both the 3-cyano and 6-dimethoxymethyl groups of 5 were converted into 2-thiazolyl groups via the thioamide and carbaldehyde groups by Hantzsch and Shioiri methods, respectively. The 2-pyridone function was changed to a bromoacetyl group via the coupling reaction between the corresponding triflate and ethyl vinyl ether, and then converted into the 4-thiazolyl group. Thus, the useful 3,6-di(2-thiazolyl)-2-(4-thiazolyl)pyridine derivative for the total synthesis of GE 2270 A was obtained. In fact, the method was recently applied to the total synthesis of an antibiotic, micrococcin P, which has a similar central skeleton.

Two 4-ethoxycarbonyl thiazolyl groups were introduced into 2- and 5-positions of 3-hydroxypyridine in 8 steps using 5-cyano-3-hydroxypyridine (2) as the starting material. The pyridine derivative obtained in the last step was converted to a fragment A derivative (21) by stepwise introduction of the 2-substituted 4-thiazolyl group into the 6-position. The total yield for the formation of 21 via 14 steps was 7.6%.

The novel antifungal karnamicin B1 (1), 5-hydroxy-3,4-dimethoxy-2-{2-(4-oxopentyl)-4-thiazolyl}pyridine-6-carboxamide was first synthesized via the formation of partially methylated trihydroxy pyridine by ring-transformation from the corresponding furan derivative and subsequent regioselective introduction of 2,6-substituents using Meisenheimer-type reaction.

Fragment A derivative (13) of nosiheptide, useful for the total synthesis, was obtained by stepwise introduction of the 2,5-bis{(4-ethoxycarbonyl)-2-thiazolyl} groups and 6-{(2-substituted)-4-thiazolyl} group into 3-hydroxy-5-cyanopyridine(3). The total yield was 7.6% via 14 steps.

The stereoselective synthesis of an amino acid component called Fragment D, N,O-diprotected 2-[(1S,3S)-1-amino-3-carboxy-3-hydroxypropyl]thiazole-4-carboxylic acid of a macrobicyclic peptide antibiotic nosiheptide, was achieved by two routes. The dipeptide, Fragment B-C, 2-[(Z)-1-(N,O-isopropylidene-L-threonylamino)-1-propenyl]thiazole-4-carboxylic acid was also synthesized by the thiazole ring formation from (Z)-2-(N,O-diprotected L-threonylamino)-2-butenethioamide with ethyl bromopyruvate. The coupling of two components by using a condensing agent gave the expected tripeptide 2, which is an important partial skeleton of the nosiheptide.

The reactions of dialkylphenylsulfonium salts (1) with several nucleophiles such as phenols, amine, enolate ion, and thiolate ions, have been investigated. The relative reactivities of the alkyl groups of sulfonium salts for the phenolate ion (hard nucleophile) were as follows; Me:Et:i-Pr =1.0:1.34:3.44. In the alkylation of the p-toluenethiolate ion (soft nucleophile) with 1, the opposite reactivity (Me:Et:i-Pr=1.0:0.22:0.03) was found. When a sulfonium salt (1e) having an optically active (S)-s-butyl group was reacted with a phenolate ion, an optically active (R)-s-butyl phenyl ether was obtained with an inversion of the configuration at the chiral carbon atom. A reaction mechanism via a sulfurane intermediate is proposed for the alkylation of the phenolate ion with alkylsulfonium salts. The relative reactivities for the alkylation of several nucleophiles with dialkylphenylselenonium salts (12) were also investigated.

The convenient syntheses of various thiazole α-dehydroamino acids, thiazole valine ethyl ester, and their dehydrodiand tripeptides, which are important moieties and segment of micrococcin P1 and noshiheptide, macrocyclic peptide antibiotics, were first accomplished.

The stereoselective synthesis of an amino acid component called Fragment D, N,O-diprotected 2-[(1S,3S)-1-amino-3-carboxy-3-hydroxypropyl]thiazole-4-carboxylic acid of a macrobicyclic peptide antibiotic nosiheptide, was achieved by two routes. The dipeptide, Fragment B-C, 2-[(Z)-1-(N,O-isopropylidene-L-threonylamino)-1-propenyl]thiazole-4-carboxylic acid was also synthesized by the thiazole ring formation from (Z)-2-(N,O-diprotected L-threonylamino)-2-butenethioamide with ethyl bromopyruvate. The coupling of two components by using a condensing agent gave the expected tripeptide 2, which is an important partial skeleton of the nosiheptide.

The novel antifungal karnamicin B1 (1), 5-hydroxy-3,4-dimethoxy-2-{2-(4-oxopentyl)-4-thiazolyl}pyridine-6-carboxamide was first synthesized via the formation of partially methylated trihydroxy pyridine by ring-transformation from the corresponding furan derivative and subsequent regioselective introduction of 2,6-substituents using Meisenheimer-type reaction.

Fragment A derivative (13) of nosiheptide, useful for the total synthesis, was obtained by stepwise introduction of the 2,5-bis{(4-ethoxycarbonyl)-2-thiazolyl} groups and 6-{(2-substituted)-4-thiazolyl} group into 3-hydroxy-5-cyanopyridine(3). The total yield was 7.6% via 14 steps.

The central heterocylic skeleton (13) of an antibiotic, A10255, was synthesized by stepwise introduction of two groups into the 2,6-positions of 3-{(4-ethoxycarbonyl)-2-thiazolyl} pyridine, via 17 steps in 4.8% total yield.

Two 4-ethoxycarbonyl thiazolyl groups were introduced into 2- and 5-positions of 3-hydroxypyridine in 8 steps using 5-cyano-3-hydroxypyridine (2) as the starting material. The pyridine derivative obtained in the last step was converted to a fragment A derivative (21) by stepwise introduction of the 2-substituted 4-thiazolyl group into the 6-position. The total yield for the formation of 21 via 14 steps was 7.6%.

It was shown that 6-dimethoxymethyl-1,2-dihydro-2-oxo-3-pyridinecarbonitrile (5) is easily convertible into the titled ring system by a stepwise method. Both the 3-cyano and 6-dimethoxymethyl groups of 5 were converted into 2-thiazolyl groups via the thioamide and carbaldehyde groups by Hantzsch and Shioiri methods, respectively. The 2-pyridone function was changed to a bromoacetyl group via the coupling reaction between the corresponding triflate and ethyl vinyl ether, and then converted into the 4-thiazolyl group. Thus, the useful 3,6-di(2-thiazolyl)-2-(4-thiazolyl)pyridine derivative for the total synthesis of GE 2270 A was obtained. In fact, the method was recently applied to the total synthesis of an antibiotic, micrococcin P, which has a similar central skeleton.

The convenient syntheses of various thiazole α-dehydroamino acids, thiazole valine ethyl ester, and their dehydrodiand tripeptides, which are important moieties and segment of micrococcin P1 and noshiheptide, macrocyclic peptide antibiotics, were first accomplished.

Partial acid hydrolysis of a new water-absorbing polysaccharide (WAP) from the family Oxalobacteraceae gave six di-, four tri-, two tetra-, two penta-, and one hexasaccharides composed of mannose, glucose, and/or galactose. The structures of oligosaccharides 1-15 were elucidated by extensive 2D NMR spectroscopic analyses. (1)H- and (13)C-NMR chemical shift assignments of oligosaccharides 1-14 are presented.

The reactions of dialkylphenylsulfonium salts (1) with several nucleophiles such as phenols, amine, enolate ion, and thiolate ions, have been investigated. The relative reactivities of the alkyl groups of sulfonium salts for the phenolate ion (hard nucleophile) were as follows; Me:Et:i-Pr =1.0:1.34:3.44. In the alkylation of the p-toluenethiolate ion (soft nucleophile) with 1, the opposite reactivity (Me:Et:i-Pr=1.0:0.22:0.03) was found. When a sulfonium salt (1e) having an optically active (S)-s-butyl group was reacted with a phenolate ion, an optically active (R)-s-butyl phenyl ether was obtained with an inversion of the configuration at the chiral carbon atom. A reaction mechanism via a sulfurane intermediate is proposed for the alkylation of the phenolate ion with alkylsulfonium salts. The relative reactivities for the alkylation of several nucleophiles with dialkylphenylselenonium salts (12) were also investigated.

The central heterocylic skeleton (13) of an antibiotic, A10255, was synthesized by stepwise introduction of two groups into the 2,6-positions of 3-{(4-ethoxycarbonyl)-2-thiazolyl} pyridine, via 17 steps in 4.8% total yield.

The title compounds were obtained by condensation of d -glucono-, d -galactono-, or l - glycero - d - gluco -heptono-1,5-lactones with methyl 2,3-di- O -(trimethylsilyl)-α- d -mannopyranosides having various substituents on C-4 and C-6, in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst. Except for a 6-acetoxyl group on a lactone component and a ( tert -butyldiphenylsiloxy) group, the usual C -substituents, such as benzyloxy, allyloxy, azido, acyloxy, (methylthio)methoxy, and methoxy, did not prevent occurrence of this condensation.

The title compounds were synthesized by condensation of 2,3,4,6-tetra- O -benzyl- d -glucono-1,5-lactone with bis- O -(trimethylsilyl)-1,2-diols in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst. Application to cis - and trans -1,2-diols containing primary, secondary, and tertiary hydroxyl groups was examined, and a new rearrangement was found in the reaction of a d -glucono-1,5-lactone derivative having an acetyl group at O-6.

A new asymmetric alkylation of cyclic β-keto esters with optically active sulfonium salts, which are easily prepared by optical resolution methods, has been investigated. Relative reactivities for alkyl substituents are found to be quite different from those for SN2 alkylation. Stereochemical reaction course via S–O sulfurane intermediate for this new reaction is proposed.

The asymmetric alkylation of 2-methoxycarbonyl-1-indanone (2) and ethyl 2-methylacetoacetate (5) with an alkylsulfonium salt containing a sugar group were investigated. (S)-Ethyl 2-allyl-2-methylacetoacetate (6b) was obtained with up to 25% optical purity on alkylation of the enolate ion of 5 using the allyl(p-tolyl)sulfonio D-glucoside derivative (1h).

Alkylation of the enolate anion of 2-methoxycarbonyl-1-indanone with optically active dialkylphenyl selenonium salt resulted in the formation of optically active C-alkylated products. Absolute configuration of the optically active selnonium ion was estimated on the basis of the asymmetric alkylation and CD spectra.

The asymmetric alkylation of 2-methoxycarbonyl-1-indanone (2) and ethyl 2-methylacetoacetate (5) with an alkylsulfonium salt containing a sugar group were investigated. (S)-Ethyl 2-allyl-2-methylacetoacetate (6b) was obtained with up to 25% optical purity on alkylation of the enolate ion of 5 using the allyl(p-tolyl)sulfonio D-glucoside derivative (1h).

Alkylation of cyclic β-keto ester with racemic sulfonium salts containing optically active alkyl groups such as (S)-2-octyl and (S)-2-butyl was found to afford C-alkylated products with inversion of configuration at asymmetric alkyl carbon atom. Stereochemical reaction course via formation of S–O sulfurane intermediate and successive stereoselective intramolecular alkyl migration to enolate is described.

A new asymmetric alkylation of cyclic β-keto esters with optically active sulfonium salts, which are easily prepared by optical resolution methods, has been investigated. Relative reactivities for alkyl substituents are found to be quite different from those for SN2 alkylation. Stereochemical reaction course via S–O sulfurane intermediate for this new reaction is proposed.