Akira Tai

Chiral specificity of the sex pheromone of the red-headed pine sawfly,Neodiprion lecontei

The stereospecificity of the sawfly pheromone 3,7-dimethyl-2-pentadecanol acetate againstNeodiprion lecontei was studied. Twoerythro and a 1∶1 mixture ofthreo isomers (C-2 and C-3) were synthesized for this purpose. It was found that only one isomer with (−)-erythro configuration (2S, 3S) had biological activity. The potency of this synthetic pheromone was roughly identical to the one shown by the naturally occurring pheromone in this species.

Field evaluation of chiral isomers of the sex pheromone of the european pine sawfly,Neodiprion sertifer

Among optical isomers of 3,7-dimethylpentadecan-2-ol (diprionol) acetate or propionate tested as synthetic attractants, the 2S, 3S, and 7S isomers were most effective in attracting the males ofNeodiprion sertifer in the field. The 2S, 3S, and 7R isomers showed weak activity, but the other optical isomers were not attractive. Capillary GC analysis showed that the natural pheromone from body extracts of females was identical with the synthetic acetate of diprionol in its GC behavior. However, the natural pheromone was about 100-fold stronger than the most purified synthetic acetate of 2S,3S,7S-diprionol in the field. As a result of various isomer combination studies, it was found that the acetate of 2S,3R,7R-diprionol, when added to 2S,3S,7S-diprionol preparation at a low concentration, increased the catch by the latter. It was therefore concluded that the above combination of the optical isomers could account for the major sex attractancy in this species.

Geographic variation in the field response of male European pine sawflies, Neodiprion sertifer, to different pheromone stereoisomers and esters.

The European pine sawfly, Neodiprion sertifer (Geoffroy) (Hymenoptera: Diprionidae), is a widespread and economically important forest insect. The sex pheromone communication system of this species has been previously investigated in North America, Japan and Europe, with the acetate or propionate of the alcohol (2S,3S,7S)‐3,7‐dimethyl‐2‐pentadecanol (diprionol) shown to be the main pheromone component. In some locations, male attraction either increased or decreased by the addition of the (2S,3R,7R)‐diprionyl acetate isomer. However, these studies were made with different batches of synthetic pheromones, with different types of traps and according to different procedures, so the observed differences might not reflect true geographic variation. Here we investigate the geographic pattern of male sawfly response by using identical chemicals, traps and experimental procedures at eight field sites ranging from Japan in the east to Canada in the west. We found an increased inhibitory effect of the (2S,3R,7R)‐isomer from Japan and Siberia to Europe. At the eastern sites, increasing amounts of the (2S,3R,7R)‐isomer up to and equal to the amount of the (2S,3S,7S )‐isomer, did not influence the trap catch, whereas at sites in Europe, as little as 1% of the (2S,3R,7R)‐isomer almost completely inhibited the attraction. The response of the North American population was intermediate. The only site in which the (2S,3R,7R)‐isomer was essential for the attraction of males was in Siberia. A similar pattern was found for the (2S,3R,7S)‐isomer. Both the acetate and the propionate form of the (2S,3S,7S)‐isomer were attractive by themselves in Japan, Europe and North America, and neither the (2S,3R,7S)‐isomer nor the (2S,3R,7R)‐isomer alone were attractive, in the acetate or propionate form. We discuss the significance of our findings for the development of more efficient monitoring schemes and for the causes of population divergence and speciation in the European pine sawfly.

Field attractiveness of chirally defined synthetic attractants to males ofDiprion similis andGilpinia frutetorum

Field attractiveness of synthetic attractants toward males of two introduced species of sawflies was examined. It was first established that the esters of 2S,3S,7S-3, 7-dimethylpentadecan-2-ol (diprionol), which have been active toward males of manyNeodiprion species, were inactive toward males ofDiprion similis andGilpinia frutetorum, To determine the chiral combination of the alcohol moiety, four different isomers, each containing specific chirally defined carbons, were synthesized. As a result it was concluded that the most active chiral arrangement of diprionol for these species is 2S, 3R, 7R.

Characterization of the Surface of Asymmetrically Modified Nickel Catalyst; An Approach for the Development of Highly Effective Enantioface-Differentiating (Asymmetric) Hydrogenation Catalyst

It has been demonstrated that there exist at least two kinds of parts (Part-I and II) in Raney nickel catalyst (RNi). When RNi is modified with tartaric acid (TA), Part-I functions as an enantioface-differentiating hydrogenation site with the aid of TA yielding an optically active product, and Part-II still acts as a non enantioface-differentiating hydrogenation site. Each part is characterized as follows. Part-II is acid-sensitive and can be reduced by the acid treatment of RNi. In addition, Part-II is poisoned by NaBr and loses its hydrogenation activity. Part-I is less sensitive to such the treatment as above and tends to adsorb TA on the treatment with TA. Thus, the treatment of RNi with an acidic solution containing TA and NaBr excludes almost all of the hydrogenation ability of Part-II from the catalyst. The resulting catalyst (TA-NaBr-MRNi) gives almost 90% of the optical yield in the hydrogenation of methyl acetoacetate to methyl 3-hydroxybutyrate.

Modification of Nickel Surface With Optically Active Substrate: The Method and Mechanism

Resume La propriete de differentiation enantioface (p.d.e.) de catalyseurs au Ni modifies par lacide tartrique (A.T.) depend de la nature du NiO precurseur et du mode de preparation. Un traitement acide du Ni reduit (HNi) avant modification par A.T., ou des modifications par A.T. a pH faible ou a haute temperature permettent dameliorer le p.d.e. Ces traitements elimineraient preferentiellement les parties amorphes de HNi correspondant a des sites de non differentiation enantioface. Abstract The enantioface-differentiating ability (e.d.a.) of tartaric acid (TA) modified reduced nickel catalyst (TA-MHNi) was found to be strongly affected by the sort of nickel oxide employed as a starting material and the preparative variations. The acidic and high temperature modification or acid-treatment of reduced nickel (HNi) before TA-modification was useful to eliminate the factors giving a low e.d.a. The amorphous parts of HNi were suggested to provide non-enantioface-differentiating sites and be preferentially eliminated by the acidic and high temperature modification or treatment.

Field Response of Male Pine Sawflies, Neodiprion sertifer (Diprionidae), to Sex Pheromone Analogs in Japan and Sweden.

The pine sawfly Neodiprion sertifer (Geoffroy) uses the acetate or propionate of (2S,3S,7S)-3,7-dimethyl-2-pentadecanol (diprionol) as pheromone components, with the (2S,3R,7R)-isomer being antagonistic, synergistic, or inactive according to the population tested. In this study, we tested the attraction of males to the acetates of three analogs of diprionol, each missing one methyl group, viz. (2S,7S)-7-methyl-2-pentadecanol, (2S,6S)-2,6-dimethyl-1-tetradecanol, and (2S,3S)-3-methyl-2-pentadecanol. None of the analogs alone, or in combination with diprionol acetate, was attractive in Sweden, even at 100 times the amount of diprionol acetate attractive to N. sertifer. In Japan, the acetate of (2S,3S)-3-methyl-2-pentadecanol attracted males when tested in amounts 10–20 times higher than the acetate pheromone component. The acetate esters of the (2S,3R)-analog and the (2S,3R,7R)-isomer of diprionol also were tested in combination with the pheromone compound (acetate ester). Both compounds caused an almost total trap-catch reduction in Sweden, whereas in Japan they appear to have relatively little effect on trap capture when added to diprionol acetate. Butyrate and iso-butyrate esters of diprionol were unattractive to N. sertifer in Sweden. In summary, there exists geographic variation in N. sertifer in responses to both diprionyl acetate and some of its analogs.

Enantio-Differentiating Hydrogenation Of Simple Alkanones With Asymmetrically Modified Heterogeneous Catalyst

The enantio-differentiating hydrogenation of 3-octanone was carried out using tartaric acid-NaBr-modified nickel catalyst and compared with that of 2-alkanones. For the hydrogenation of 3-octanone, fine nickel powder was a better source of the catalyst than Raney nickel. 3-Octanone was hydrogenated with an optical yield of 30% over tartaric acid-NaBr-fine nickel powder. As for the effect of hydrogenation temperature on optical yield, hydrogenation at a lower temperature resulted in a lower optical yield for the hydrogenation of 3-octanone, while the lower temperature resulted in a higher optical yield for the hydrogenation of 2-alkanones.