Akio Ohnishi

Pyrolytic formation of 3-hydroxy-2-penteno-1,5-lactone from xylan, xylo-oligosaccharides, and methyl xylopyranosides

Abstract Xylan, xylotriose, and xylobiose were heated for 3 sec at 386 and 423° in helium as carrier gas. The major, volatile decomposition-products of the foregoing compounds were 3-hydroxy-2-penteno-1,5-lactone and 2-furaldehyde. Lactone formation also occurred on pyrolysis of methyl α- and β-D-xylopyranosides, although the yields of volatile products were very low, except for methanol, which was derived from the aglycon. The relative yield of the lactone decreased as the number of non-reducing xylopyranosyl residues in the molecule decreased. None of the lactone could be found in the pyrolyzate of D-xylose, whereas 2-furaldehyde was formed from all of the samples. These results suggest that 3-hydroxy-2-penteno-1,5-lactone is formed independent from the formation of 2-furaldehyde, and that the lactone arises from the non-reducing xylopyranosyl residues in the molecule. The results of dynamic thermal analyses of xylan, xylo-oligosaccharides, D-xylose, and methyl β-D-xylo-pyranoside are also reported.

Inhibitory action of (4S,6S,7R)-isomer to pheromonal activity of serricornin, (4S,6S,7S)-7-Hydroxy-4,6-dimethyl-3-nonanone

By adding the effects of a series of the stereoisomers to the pheromonal activity of serricornin, (4S,6S,7S)-7-hydroxy-4,6-dimethyl-3-nonanone, the sex pheromone of the cigarette beetleLasioderma serricorne (F.) was investigated. The experiments using synthetic enantiomeric mixtures and optically active stereoisomers showed that the (4S,6S,7R)-isomer inhibited significantly the pheromonal activity of serricornin.

Inhibition of male response of drugstore beetles to stegobinone by its isomer.

Stegobinone, (2S, 3R, 1′R)-2,3,-dihy dro-2,3,5-trimethyl-6-(1′-methyl-2′-oxobutyl)-4H-pyran-4-one, the sex pheromone of drugstore beetles (Stegobium paniceum L.), elicited the pheromonal response from the males of the species in our bioassay system; however, the synthesized diastereomeric mixture of this compound was actually inactive to the males. Although the stegobinone isolated from the beetles of this species had significant activity, its enantiomeric [(±)-2S,3R,1′S-] and diatereomeric [(±)-2S,3S,1′RS-] isomers were inactive. Adding the (±)-2S,3R,1′S isomer to stegobinone significantly reduced the male response. Furthermore, the activity of Stegobinone vanished on keeping it at room temperature for two weeks. In such a stored stegobinone sample, the presence of 2S,3R,1′S isomer, the inhibitory component, was confirmed. This isomer might be produced by C-1′ epimerization during storage.

Stegobiol, a new sex pheromone component of drugstore beetle (Stegobium paniceum L.).

New sex pheromone component of femaleStegobium paniceum L. was isolated and identified as 2,3-dihydro-2,3,5-trimethyI-6-(1′-methyl-2′-hydroxybutyl)-4H-pyran-4-one, stegobiol, by spectral data and chemical conversion from stegobinone. Relative configuration at C-2, C-3, and C-1′ was determined as 2S,3R,1′S by the conversion from (2S,3R,1′R)-stegobinone. This new sex pheromone elicits the pheromonal response from the species.

A pectic polysaccharide from cell walls of tobacco (Nicotiana tabacum) mesophyll

Abstract A pectic polysaccharide has been purified from the pectin fraction of the cell-wall material of tobacco mesophyll by ion-exchange chromatography and gel filtration, and shown to contain d -galacturonic acid, l -rhamnose, l -arabinose, and d -galactose in the molar ratios 88.2:2.8:3.1:5.9. The polysaccharide contains at least three regions, namely, galacturonan, rhamnogalacturonan, and galactan.

Reinvestigation of anhydroserricornin, (2S,3S)-2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran, as a sex pheromone component for male cigarette beetle

Reinvestigation of the pheromonal activity of anhydroserricornin, (2S,3S)-2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran, showed that the magnitude of its activity was less than 1/103 of that of serricornin, 7-hydroxy-4,6-dimethyl-3-nonanone, the sex pheromone of the cigarette beetleLasioderma serricorne (F.). Neither a synergistic nor an inhibitory effect of anhydroserricornin addition on the action of serricornin was observed.

Crystal structure and 1H- and 13C-n.m.r. studies of 1,4:3,6-dianhydro-α-d-glucopyranose obtained from pyrolysis of cellulose

Abstract The crystal structure of a compound obtained by pyrolysis of cellulose, whose chemical structure has been proposed as 1,4:3,6-dianhydro-α- d -glucopyranose, has been confirmed by X-ray crystallographic analysis. Proton- and 13C-n.m.r. measurements were also made on it and the relationship between n.m.r.-spectroscopic and X-ray crystallographic results is discussed.

Cembrane-derived diterpenoid having a carbotricyclic skeleton

Abstract A novel carbotricyclic diterpenoid, 18-oxo-3-virgene, has been isolated from the waxy, surface resins of tobacco. Its structure was determined by spect