Hirosato Takikawa

Diastereoselective epoxidation of the double bond at C-4 of sphingosines to provide phytosphingosine relatives such as α-galactosylceramide KRN7000☆

Abstract Diastereoselective epoxidation of the double bond at C-4 of two sphingosine derivatives [3, R = (CH2)7Me or (CH2)12Me] was studied. Dimethyldioxirane was found to be the best oxidant for that purpose. Application of this epoxidation resulted in a new synthesis of the α-galactosylceramide KRN7000 (2), which has an enhancing effect on the activity of natural killer cells.

Synthesis of penaresidin a, an azetidine alkaloid with actomyosin ATPase-activating property

Three stereoisomers of penaresidin A (1), an azetidine alkaloid isolated from the Okinawan marine sponge Penares sp., were synthesized. The natural penaresidin A must be either (2S,3R, 4S,15S,16S)- or (2S,3R, 4S, 15R,16R)-1.

ABSOLUTE STEREOCHEMISTRY OF PENARESIDINS A AND B

Absolute stereochemistry at C-15 in penaresidins A (1) and B (2) was established to be S on the basis of 1H NMR data of the tri-O-MTPA esters, indicating that the absolute configurations of 1 and 2 are 2S, 3R, 4S, 15S (1 and 2), and 16S (1).

SYNTHESIS AND ABSOLUTE CONFIGURATION OF SORDIDIN, THE MALE-PRODUCED AGGREGATION PHEROMONE OF THE BANANA WEEVIL, COSMOPOLITES SORDIDUS

The racemate as well as both the enantiomers of sordidin (1-ethyl-3,5,7-trimethyl-2,8-dioxabicyclo[3.2.1]octane, 1) were synthesized, and the natural pheromone was shown to be (1S,3R,5R,7S)-(+)-1.

Synthesis of the Enantiomers of Some Methyl-branched Cuticular Hydrocarbons of the Ant, Diacamma sp.

The enantiomers of 3-methylpentacosane, 3-methylheptacosane, 3-methylnonacosane, 13-methylheptacosane, and 5-methylheptacosane were synthesized by starting from the enantiomers of 2-methylbutyl bromide or citronellol. These methyl-branched alkanes are the characteristic components of the cuticular hydrocarbons of queen of the ant, Diacamma sp.

A new synthesis of the four stereoisomers of 3,11-dimethyl-2-nonacosanone, the female-produced sex pheromone of the German cockroach

Abstract The pure four stereoisomers of 3,ll-dimethyl-2-nonacosanone (1), the female-produced sex pheromone of the German cockroach, were synthesized starting from ( R )-citronellol ( 2 a) and ethyl ( R )-3-hydroxybutanoate ( 3 ). The key step was the chromatographic separation of (5RS,6R)-6-hydroxy-5-methyl-2-heptanone ( 16 a) to give pure ( 5R,6R - and) 5S,6R -isomers. All of the four stereoisomers of 1 were bioactive.

A new synthesis of the enantiomers of ipsdienol, the pheromone of the IPS bark beetles☆

Abstract The enantiomers (~96% e.e.) of ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol, 1a ) were synthesized from the enantiomers of serine ( 5 ) in 16–21% overall yield in 8 steps.

DOES PHEROMONE BIOLOGY OF Lambdina athasaria AND L. pellucidaria CONTRIBUTE TO THEIR REPRODUCTIVE ISOLATION

Recently, 7-methylheptadecane and 7,11-dimethylheptadecane have been reported as sex pheromone components of both spring hemlock looper (SHL), Lambdina athasaria, and pitch pine looper (PPL), Lambdina pellucidaria. Our objective was to test the hypothesis that SHL and PPL are reproductively isolated, in part, through species specificity in: (1) absolute configuration of pheromone components, (2) diel periodicity of pheromonal communication, and/or (3) seasonal flight period. In coupled gas chromatographic–electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized (7S)and (7R)-7-methylheptadecane [7S; 7R] as well as (7S,11S)-, (7R,11R)-, and (meso-7,11)-7,11-dimethylheptadecane [7S,11S; 7R,11R; meso-7,11], only 7S and meso-7,11 elicited responses by male SHL and PPL antennae. In field experiments, male SHL and PPL were attracted only to lures containing 7S plus meso-7,11. In hourly recordings of trap-captured males, SHL and PPL in their respective habitats were trapped between 24:00 and 03:00 hr. Capture of both SHL and PPL in pheromone-baited traps throughout June indicated overlapping seasonal flight periods. These findings of identical absolute configuration of pheromoal components, diel periodicity of pheromonal communication, and overlap of seasonal flight periods support synonymy of SHL and PPL. Finite taxonomic classification of PPL and SHL must await careful assessment of further criteria, such as morphometrics, molecular comparisons and ecological analyses.

SYNTHESIS OF SULFOBACIN A AND B, NEW SULFONOLIPIDS ISOLATED FROM CHRYSEOBACTERIUM SP.

Sulfobacin A (1) and B (2), new sulfonolipids isolated from Chryseobacterium sp. as von Willebrand factor antagonists, were synthesized stereoselectively by starting from l-cysteine.

Enzymatic resolution of (±)-γ-cyclohomogeraniol and conversion of its (S)-Isomer to (S)-γ-coronal, the ambergris odorant

Enzymatic acetylation of (±)-γ-cyclohomogeraniol[2-(2′,2′-dimethyl-6′-methylenecyclohexyl)ethanol] with vinyl acetate in the presence of lipase AK yielded the acetate of its (R)-isomer, leaving its (S)-isomer intact. The (S)-isomer was chemically converted to (S)-γ-coronal[2-methylene-4-(2′,2′-dimethyl-6′-methylenecyclohexyl)butanal], the ambergris odorant.