[Identification of corrected retention indices of ten phenols in reversed-phase high performance liquid chromatography]

Corrected retention indices in RP-HPLC of ten phenols based on 2-keto-alkanes were examined on three ODS-silica columns. The RI values for phenols showed large variations. However, when the correction was applied, the variations diminished significantly. It is clear that the correction procedure improves the variation of phenols' RI values obtained from different ODS columns. The procedure is recommended as a method of standardization of HPLC data.

Synthesis and utility of 2-(benzoyloxyimino)-2-deoxy-alpha-D-lyxo-hexopyranosyl bromide as a novel alpha-D-talosaminide building block

A novel alpha-D-talosaminyl donor, 2-(benzoyloxyimino)-2-deoxy-alpha-D-lyxo-hexopyranosyl bromide has been synthesized in a total yield of 32% over 6 steps from D-galactose. The utility of the donor was evaluated for the elaboration of alpha-D-TalNAc-(1-->6)-alpha-D-Gal, alpha-D-TalNAc-(1-->6)-alpha-D-Glc, and alpha-D-TalNAc-(1-->3)-L-serine derivatives by a simple 3-step sequence, comprising alpha-selective glycosylation of appropriately protected acceptors of D-galactose, D-glucose, and L-serine, talo-selective hydroboration of the oxyimino function to an amino group, and N-acetylation.

Syntheses of three interglycosidic isomers of N-acetyl-beta-D-mannosaminyl-L-rhamnoses associated with O-antigens of several gram-negative opportunistic pathogens

We achieved practical, highly stereoselective syntheses of three interglycosidic isomers of N-acetyl-beta-D-mannosaminyl-L-rhamnoses, among which a beta(1-->4)-isomer corresponds to the repeating unit of the O-antigen of lipopolysaccharide (LPS) from the opportunistic pathogens Pseudomonas cepacia O5 and Pseudomonas aeruginosa X (Meitert). The other isomers are a beta(1-->2)-disaccharide, a constituent of LPS from Escherichia coli O1A, and an artificial beta(1-->3)-isomer. The disaccharides were obtained by simple three-step reaction sequences from 2-(benzoyloxyimino)-2-deoxyglycosyl halides (mannosamine progenitor). beta-Selective glycosylations of appropriately protected L-rhamnosyl acceptors were performed. Subsequent reduction of the 2-acyloxyimino function to an amino group, N-acetylation, and removal of the protecting groups provided the target disaccharides. 13C-NMR and nuclear Overhauser effect spectra proved to be useful for structural determination of the positional isomers of the disaccharides.

[Reaction of 3-aryl-2-nitroacrylates with titanium tetrachloride. Formation of 4H-1,2-oxazines and hydroxy-arylaldehydes]

The reaction of ethyl 3-aryl-2-nitroacrylate (1a: aryl = 3-methoxyphenyl) with toluene in the presence of titanium tetrachloride gave 4-(4'-methyl-phenyl)-4H-1,2-benzoxazine (3) in a 44.2% yield. The acrylate 1a reacted with dichloromethane in the presence of titanium tetrachloride to give 5-methoxy-salicylaldehyde (2a) in a 61.8% yield. Therefore, 2a was presumed to be formed via an intermediate 4H-1,2-benzoxazine (3'), followed by ring opening to quinone methide and cyano formate. In a similar reaction using both toluene and dichloromethane, 1 bearing a 2-naphthyl group gave a dimer of quinone methide and 1-hydroxy-2-naphthaldehyde via 4H-naphth[2,1-e]-1,2-oxazine, respectively.

[Synthesis and antimicrobial properties of methyl 3-O-alkyl-glucopyranosides]

A new type of nonionic surface-active agents containing sugars as the hydrophilic group were synthesized and evaluated for their antimicrobial activity. Methyl 6-deoxy-3-O-dodecyl-6-halo-D-glucopyranoside derivatives showed powerful antimicrobial activity, but no significant differences were observed on the activity with regard to the kinds of anomers as well as halogen atoms.

[Synthesis and antibacterial properties of 3-O-alkyl-D-glucose derivatives]

A series of 3-O-alkyl-1,2-O-isopropylidene-alpha-D-glucofuranoses (3-7), 6-deoxy-3-O-dodecyl-6-halo-1,2-O-isopropylidene-alpha-D-glucofuranose s (9-11), and 6-deoxy-3-O-dodecyl-6-halo-D-glucopyranoses (12-14) were prepared from 1,2; 5,6-di-O-isopropyridene-alpha-D-glucofuranose and their antibacterial activities were evaluated. The compounds having C12 and C14 alkylchains at C-3 of 1,2-O-isopropylidene glucoses were the most effective in vitro antibacterial screening, of which the structure-activity relationships are also discussed.

[Synthesis and antimicrobial properties of 3-O-alkyl and 3-O-haloalkyl-D-glucoses]

A series of 3-O-alkyl and 3-O-haloalkyl-D-glucoses were prepared from 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose and their antibacterial activities were evaluated. The compounds with C12 and C14-alkyl chains were the most effective in vitro antibacterial screening, among 3-O-alkyl and 3-O-haloalkyl derivatives. The 3-O-alkyl derivatives were more effective than 3-O-haloalkyl derivatives.