Shigefumi Kuwahara

Male-released sex pheromone of the stink bug Piezodorus hybneri

Male-released semiochemicals of the stink bug Piezodorus hybneri (Heteroptera: Pentatomidae) elicit attraction of male and female bugs and homosexual behavior in males. Three active components were isolated from the airborne volatiles of males by flash chromatography, with the activity monitored by GC-EAD and behavioral bioassay. The pheromone system was characterized as a mixture of β-sesquiphellandrene, (R)-15-hexadecanolide, and methyl 8-(Z)-hexadecenoate (ratio: 10:4:1), and the activity of the semiochemicals was assessed with authentic samples. Enantiomerically pure samples of the R and S macrolactones were obtained by Yamaguchis and Mitsunobus macrolactonization of a key intermediate, (R)-15-hydroxyhexadecanoic acid. The nonnatural S stereoisomer was neither a beneficial nor a behavioral antagonist. Individual constituents or binary mixtures were active, but the optimal male response was elicited only by the full mixture. Behavioral observation and the fact that the onset of pheromone production is coincident with ovarian development strongly suggest that these semiochemicals are, in fact, sex pheromones.

Synthesis of (22S, 23S)-homobrassinolide and brassinolide from stigmasterol

Abstract (22S, 23S)-Homobrassinolide (2α, 3α, 22S, 23S-tetrahydroxy-24S-etyl-B-homo-7-oxa-5α-cholestan-6-one) and brassinolide (2α, 3α 22R, 23R-tetrahydroxy-24S-methyl-B-homo-7-oxa-5α-cholestan-6-one) were synthesized from stigmasterol and shown to promote plant growth.

Stereochemistry of lardolure the aggregation pheromone of the acarid mite, Lardoglyphus konoi

Abstract 1R , 3R , 5R , 7R -Stereochemistry was assigned to lardolure (1,3,5,7-tetramethyldecyl formate) on the basis of GLC comparision of the natural pheromone with the synthetic pheromones prepared in partially stereocontrolled manners.

Synthesis of all of the four possible stereoisomers of 4,8-dimethyldecanal, the aggregation pheromone of the flour beetles

Abstract The four stereoisomers of 4,8-dimethyldecanal were synthesized employing organometallic or electrolytic coupling reactions as the key-step. The response of the red flour beetle, Tribolium castaneum , to the ( 4R , 8R )-isomer was identical with that to the natural pheromone, while other isomers induced only very weak or no responses. The ( 4R , 8R )-isomer is therefore the natural pheromone.

Synthesis of both the enantiomers of lardolure, the aggregation pheromone of the acarid mite, lardoglyphus konoi

Abstract Both the enantiomers of lardolure were synthesized in 100 % optical purity and 99.6 % diastereomeric purity by use of Fraters diastereoselective alkylation as the key-step. Since ( 1R , 3R , 5R , 7R )-enantiomer showed the same ORD sign and bioactivity as those shown by the natural pheromone, the structure of lardolure was established unambiguously as ( 1R , 3R , 5R , 7R )-1,3,5,7-tetramethyldecyl formate.

Synthesis and biological activity of both (E)- and (Z)-isomers of optically pure (S)-14-methyl-8-hexadecenal (trogodermal), the antipodes of the pheromone of the khapra beetle

Abstract Both ( E )- and ( Z )-isomers of ( S )-14-methyl-8-hexadecenal (trogodermal) were synthesized from 100% optically pure ( R )-(+)-citronellic acid. These antipodes of the khapra beetle pheromone were 1/500 to 1/1000 times as active as the natural ( R )-pheromone. Determination of the optical purities of citronellic acid and related compounds was achieved by hplc method. Warning was made not to forget the measurement of density in expressing the optical rotation of a neat liquid as [α] D (neat).

(R,Z)-7,15-Hexadecadien-4-olide, sex pheromone of the yellowish elongate chafer, Heptophylla picea

An active component of the sex pheromone system of the yellowish elongate chafer, Heptophylla picea was identified by GC-EAD. Mass spectral data and hydrogenation revealed that the active compound was a hexadecadien-4-olide. It was not possible to determine the double bond positions by direct DMDS derivatization of the pheromone, but partial hydrogenation (diimide) followed by DMDS derivatization showed that the double bonds were located in positions 7 and 15. FTIR (tracer) of the pheromone corroborated the lactone structure (1772 cm-1) and showed a band characteristic of a terminal double bond at 3073 cm-1, and one of a double bond in the cis-configuration at 3002 cm-1. Chiral resolution of the pheromone, after hydrogenation, demonstrated that the natural lactone had the (R)-stereochemistry. Synthetic (R,Z)-7,15-hexadecadien-4-olide, prepared from L-malic acid in 14 steps, was identical to the natural product in MS, IR, retention times and biological activity. This is the first fatty acid derivative compound found as a sex pheromone of a Melolonthinae species and as far as biosynthesis is concerned this is the most complex pheromone constituent of a scarab species.

Synthesis of optically active forms of (E)-6-isopropyl-3,9-dimethyl-5,8-decadienyl acetate, the pheromone of the yellow scale☆

Abstract Highly optically pure enantiomers of ( E )-6-isopropyl-3,9-dimethyl-5,8-decadienyl acetate, the sex pheromone of the yellow scale ( Aniodiella citrina ), were stereoselectively from synthesized from( R )-(+)-citronellic acid. Only the ( s )-enantiomer was bioactive.

Synthesis of (-)-periplanone-B a sex pheromone component of the American cockroach (periplaneta americana)

Abstract The naturally occurring (-)-enantiomer of periplanone-B was synthesized stereoselectively starting from ( S )-3-cyclohexene-1-carboxylic acid. The crystalline pheromone was obtained in 12% overall yield through 18 steps.

Synthesis of both the enantiomers of Hauptmann's periplanone-A and clarification of the structure of Persoons's periplanone-A.

Abstract The naturally occurring (-)-enantiomer of Hauptmanns periplanone-A and its stereoisomers were synthesized. Thermal rearrangement of Hauptmanns (-)-periplanone-A by GLC gave Persoonss periplanone-A, the structure of which was determined through an X-ray crystallographic analysis of the corresponding alcohol.