[Show abstract][Hide abstract] ABSTRACT: Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce three sex pheromone components (I-III), for which we assigned the following novel chemical structures; 6-methyl-2-octadecanone (1) for I, 14-methyl-2-octadecanone (2) for II, and 6,14-dimethyl-2-octadecanone (3) for III. In the Iriomote Islands where the insects were collected, a lure including racemic 1 and 2 attracted the male moths without mixing 3. In this study for further confirmation of the plane structures, the positional isomers with a methyl branch at the 4-, 5-, 7-, 13-, or 15-position (4-8, respectively) were synthesized. The GC-MS analyses revealed that natural components I and II were best fitted with those of 1 and 2, respectively, among the methyl-2-octadecanones examined, indicating the usefulness of this analytical instrument and authentic standards for the determination of the positions of methyl branches. In field trapping tests, 4-8 could not substitute for 1 or 2, nor did these compounds inhibit the active binary lure of 1 and 2, indicating that the males strictly recognized the 2-ketones with a methyl branch at the 6- or 14-positions. Next, the absolute configurations of I and II were determined by HPLC with a normal-phased chiral column (Chiralpak AD-H), which could separate the enantiomers of both 1 and 2. The chiral HPLC analysis of a crude pheromone extract indicated that the females exclusively produced (S)-1 and (S)-2. Furthermore, a field evaluation of each enantiomer revealed that (S)-1 and (S)-2 were bioactive but (R)-1 and (R)-2 were not.
No preview · Article · Aug 2010 · Journal of Chemical Ecology
[Show abstract][Hide abstract] ABSTRACT: Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce a novel sex pheromone composed of three methyl-branched ketones: 6-methyl-2-octadecanone (I), 14-methyl-2-octadecanone (II), and 6,14-dimethyl-2-octadecanone (III). Their structures were confirmed by syntheses accomplished by a different route for each component. In order to obtain a sufficient amount of the synthetic pheromone, we developed new routes via methyl-branched 1-alkenes: 6-methyl-1-octadecene (1), 14-methyl-1-octadecene (2), and 6,14-dimethyl-1-octadecene (3). Compound 1 was synthesized by coupling between a C(10)-chain bromide and a 3-methyl-branched C(8) unit (A) prepared from 3-methyl-1,5-pentanediol, 2, by coupling between a C(11)-chain bromide and a 3-methyl-branched C(7) unit (B) prepared from 2-hexanone, and 3, by connecting A and B, using propargyl alcohol as a C(3) linchpin. The use of 3-chloro-1-propanol and tert-butyl acetoacetate as the linchpin was also examined to connect the two synthetic blocks in the synthesis of 3. Components I-III were obtained by Wacker oxidation of the corresponding 1-alkenes 1-3 in good yields.
No preview · Article · Jan 2010 · Bioscience Biotechnology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: (6Z,9Z,12Z)-6,9,12-Octadecatriene and (3Z,6Z,9Z,12Z)-3,6,9,12-icosatetraene, hydrocarbons unsaturated more highly than usual lepidopteran Type II pheromones, were identified from geometrid females of Hemithea tritonaria and Thalassodes immissaria intaminata, respectively. The triene was synthesized by a double Wittig reaction between hexanal and an ylide derived from (Z)-1,6-diiodo-3-hexene, and the tetraene was synthesized by a coupling between (Z)-3-undecenal and an ylide derived from (3Z,6Z)-1-iodo-3,6-nonadiene. Each synthetic compound attracted males of the corresponding emerald moths in a field.
No preview · Article · Aug 2009 · Tetrahedron Letters
[Show abstract][Hide abstract] ABSTRACT: Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce a novel sex pheromone composed of three methyl-branched ketones (I-III) in a ratio of 2:1:1. In order to confirm the structure of III (6,14-dimethyl-2-octadecanone), a mixture of its four stereoisomers was synthesized via chain elongation by two Wittig reactions, starting from 1,7-hexanediol. GC-MS data of the synthetic III were satisfactorily coincident with those of the natural component. In addition to the racemic mixtures of I (6-methyl-2-octadecanone) and II (14-methyl-2-octadecanone), previously synthesized, the activity of III was evaluated in the Iriomote Islands, and effective male attraction was observed for the 2:1:1 mixture of I-III. This result indicates that the females do not produce only one stereoisomer for each component or that the response of the males is not disturbed by the other stereoisomers of natural isomers produced by the females. The field test also revealed that the two-component lure of I and II captured as many males as the mixture of I-III, while lures baited with two components in other combinations and with only one component scarcely exhibited any male attraction ability.
No preview · Article · Aug 2009 · Bioscience Biotechnology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produced three pheromone components (I-III), which strongly stimulated male antennae. Using GC-MS analysis and chemical derivatizations, the following structures were estimated: 6-methyl-2-octadecanone (I), 14-methyl-2-octadecanone (II), and 6,14-dimethyl-2-octadecanone (III). While the stereochemistry of the chiral centers could not be determined because it was difficult to collect a sufficient amount of the natural pheromone, the plain structures of I and II were confirmed by synthesis of the racemic mixtures starting from diols. These methyl-branched ketones have not been identified as a natural product, indicating that they constitute a new chemical group of lepidopteran female sex pheromones.
No preview · Article · Dec 2007 · Bioscience Biotechnology and Biochemistry