Effects of bis homoallylic and homoallylic hydroxyl substitution on the olefinic 13C resonance shifts in fatty acid methyl esters.

Substitution of a hydroxyl group at the bis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73 +/- 0.05 ppm upfield and a 0.73 +/- 0.06 ppm downfield shift on the delta and epsilon olefinic 13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of the bis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [formula: see text] where delta delta dbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the delta and epsilon shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [formula: see text] In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the gamma and delta induced hydroxyl shifts for the cis double bond resonances are +3.08 and -4.63 ppm, respectively while the trans double bond parameters are +4.06 and -4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [formula: see text] for cis and [formula: see text] for the trans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations for cis and trans isomers are [formula: see text] and [formula: see text] respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Methyl-branched octanoic acids as substrates for lipase-catalyzed reactions.

Hydrolyses of racemic methyl-branched octanoic acid thiolesters are described using six commercial lipases as catalysts. Branching at positions 2, 4 and 5 greatly reduced activity; branching at the 3-position virtually eliminated activity. The reactivities of the racemic branched thiolesters relative to the unbranched ester were very similar for each lipase preparation examined. In reactions involving configurationally pure 2-methyloctanoic acids, the S-enantiomer reacted faster both in esterification of aliphatic alcohols and in hydrolyses of aliphatic alcohol esters with all of the lipases examined. Stereobiases in hydrolyses of the octanoic acid esters branched at other positions were low and variable. In sharp contrast to the hydrolyses of the thiolesters of 2-methyloctanoic acid, two aryl esters of 2-methyloctanoic acid catalyzed by R. miehei lipase hydrolyzed with a bias for the R-configuration. A view of the ester-enzyme complex is offered to explain the relative rates of reaction of the racemic esters.

Trimedlure enantiomers: Differences in attraction for mediterranean fruit fly,Ceratitis capitata (Wied.) (Diptera: Tephritidae).

The most biologically active enantiomer of trimedlure, a synthetic lure attractive to male Mediterranean fruit flies, is the 1S,2S,4R enantiomer of isomer C, the fert-butyl ester of ris-4-chloro-trans-2-methylcyclohexanecarboxylic acid. We also determined that the 1R,2R,5S enantiomer of isomer A is significantly more attractive than its optical antipode. Essential differences in the current synthetic work that are critical to possible commercialization of this preparation are detailed herein.

Responses of braconid parasitoidsMicroplitis croceipes (Cresson) andM. demolitor Wilkinson to stereoisomers of kairomone 13-methylhentriacontane.

The responses ofMicroplitis croceipes (Cresson) andMicroplitis demolitor Wilkinson to theR andS stereoisomers of the kairomone 13-meth-ylhentriacontane were evaluated. Singly and in combination at 5, 50-, and 500-ng dosage levels each were tested. There was a linear dosage response by both species to the three dosages. Furthermore, there was no difference between responses to the two stereoisomers or their combination by either species at any dosage level. The effects of the two stereoisomers were fully interchangeable and additive. This is the first report of parasitoid responses to stereoisomers of a kairomone.

Stereoisomers and analogs of 14-methyl-1-octadecene, sex pheromone of peach leafminer moth,Lyonetia clerkella, L.

The synthesis of the enantiomeric 14-methyl-1-octadecenes in >99% EE is described. Enantiomeric 2-methyl-1-hexanols were intermediates in the synthesis. The 1-alkene had been previously identified as the sex pheromone of the peach leafminer moth. Several closely related structures that have δ12 unsaturation are also described.

Kinetic resolution of secondary alcohols with commercial lipases : Application to rootworm sex pheromone synthesis.

The relative rates of enzyme-catalyzed esterification of the enantiomers of 2-octanol with various acids were determined for several commercial lipases. Interesterifications and hydrolyses of racemic 2-octanol esters catalyzed by these enzymes were also examined. Novo'sMucor miehei lipase exhibited considerable enantioselectivity and was therefore employed to prepare 8-methyl-2-decanols with high configurational purity at the carbinol carbon. Esters of these alcohols had been previously identified as sexually attractive to several rootworm (Diabrotica) species, and the stereochemistry of those esters had been shown to be critical to the attraction. The enzymatic resolution provides a convenient method to obtain such esters in a desired state of configurational purity.

Identification of sex pheromone produced by female sweetpotato weevil,Cylas formicarius elegantulus (Summers).

A sex pheromone of the sweetpotato weevil,Cylas formicarius elegantulus (Summers), was obtained from collections of volatiles from virgin females, and pheromone was isolated by means of liquid and gas chromatography. The purification procedure was monitored by quantitative laboratory and field bioassays and the compound was identified as (Z)-3-dodecen-1-ol (E)-2-butenoate by means of spectroscopic and microchemical methods. Synthesis, followed by laboratory and field bioassays, showed that the biological activity of the synthetic material was qualitatively and quantitatively indistinguishable from that of the purified natural product.

Response of northern corn rootworm,Diabrotica barberi Smith and Lawrence, to stereoisomers of 8-methyl-2-decyl propanoate.

The four stereoisomers of 8-methyl-2-decyl propanoate were tested in South Dakota for attractiveness to the northern corn rootworm,Diabrotica barberi Smith and Lawrence (NCR). Only the 2R,8R configuration was attractive to the NCR. Inhibition of the NCR response to 2R,8R occurred when either the 2S,8R or 2S,8S isomers were components of the pheromone source. The 2R,8S configuration elicited no behavioral activity in the NCR.

Synthesis of stereoisomers of 8-methyl-2-decanol and esters attractive to severalDiabrotica sp.

Details of the syntheses of the four stereoisomers of 8-methyl-2-decanol and its propanoate ester are given. The racemic ester, two of its stereoisomers, and one stereoisomer as an acetate are attractive to several species ofDiabrotica. The key steps in the syntheses involve high-performance liquid chromatograpic resolutions of diastereomers to achieve high configurational enrichment of each site and generation of (R)-2-methylbutyric acid by chemical degradation ofD-isoleucine.

General approach to synthesis of chiral branched hydrocarbons in high configurational purity.

Configurationally pure (>99.6%) α-methylalkanoic acids have been employed to prepare chiral hydrocarbon semiochemicals. The stereoisomers of the following compounds were synthesized: 13-methylhentriacontane, 15-methyltritriacontane, and 15,19-dimethyltritriacontane. The first compound was identified earlier as a kairomone of the corn earworm while the other two are sex excitants of the stable fly. The methods described have broad applicability in asymmetric synthesis.

Response ofDiabrotica virgifera virgifera, D. v. Zeae, andD. porracea to stereoisomers of 8-methyl-2-decyl propanoate.

The four stereoisomers of 8-methyl-2-decyl propanoate were tested in the United States and Mexico for attractiveness toDiabrotica virgifera virgifera LeConte, the western corn rootworm,D. v. zeae Krysan and Smith, the Mexican corn rootworm, andD. porracea Harold. Males ofD. v. virgifera andD. v. zeae responded strongly to the (2R,8R)-isomer and secondarily to (2S,8R), whileD. ponacea responded exclusively to the (2S,8R)-isomer. The (2S,8S)- and (2R,8S)-isomers were inactive in all tests. Synergism or inhibition was not detected when various mixtures of the isomers were tested withD. v. virgifera. These phenomena were not tested withD. v. zeae andD. ponacea.

Improved preparations of alkyne nitriles, acetates, and alcohols : Application to the synthesis of the sex pheromone components of the Douglas fir tussock moth and peach fruit moth.

One-pot conversions of terminai alkynes to cyanoethylated and cyanopropylated alkynes are described. Reactions of these nitriles with Grignard reagents produced alkynones, the reductions of which gave alkenones. The described routes provide 3-step syntheses of several insect sex or stimulatory pheromones, namely, those of the peach fruit moth (Carposina niponensis Walsingham), Douglas fir tussock moth (Orgyia pseudotsugata [McDunnough]), and housefly (Musca domestica L.). Additionally, potentially useful one-pot processes for the preparation of hydroxyalkylated and acetoxyalkylated alkynes are reported.

Identification of a female-produced sex pheromone from the southern corn rootworm,Diabrotica undecimpunctata howardi Barber.

A sex pheromone has been isolated and identified from virgin females of the southern corn rootworm (SCR),Diabrotica undecimpunctata howardi Barber. The synthesized compound, 10-methyl-2-tridecanone was shown to be attractive to males of the SCR, and also to males ofD. u. undecimpunctata Mannerheim, the western spotted cucumber beetle (WSCB), and ofD. u. duodecimnotata in Mexico. Males of both the SCR and the WSCB strongly preferred theR over theS enantiomer. The resolved enantiomers were not tested againstD. u. duodecimnotata.

Synthesis of (±)-10-methyl-1-dodecanol acetate, the chiral component of the smaller tea tortrix moth (Adoxophyes sp.), with an option for asymmetric induction.

A new route to (±)-10-methyl-1-dodecanol acetate, a minor component of the smaller tea tortrix moth (Adoxophyes sp.), is described. An optional sequence that permits the generation of the chiral center with enantiomeric excesses (ee's) as high as 74% (R) or 80% (S) employing the available (S)-(-)-prolinol as a chiral auxiliary may be included. High-performance liquid chromatography of diastereomeric intermediates allows preparation of products with greater ee's.

Identification of a female-produced sex pheromone of the western corn rootworm.

A sex pheromone has been isolated and identified from virgin females of the western corn rootworm (WCR),Diabrotica virgifera virgifera LeConte. The synthesized compound, racemic 8-methyl-2-decanol propanoate, was equal in attraction to the natural pheromone when tested in the field as a trap bait against three taxa ofDiabrotica known to respond to pheromone extracts from female WCR. Five taxa (D. virgifera virgifera; D. virgifera zeae Krysan and Smith, Mexican corn rootworm;D. longicornis barberi Smith and Lawrence, northern corn rootworm;D. longicornis longicornis (Say); andD. porracea Harold) were attracted to traps baited with 8-methyl-2-decanol propanoate. The response of male northern corn rootworms (NCR) in the field peaked at a relatively low concentration of 8-methyl-2-decanol propanoate and then was severely reduced at the higher concentrations tested. Conversely, the response of male WCR in the field continued to increase up to the highest dose tested.

Insect sex pheromones: minor amount of opposite geometrical isomer critical to attraction.

(Z)-II-Tetradecenyl acetate is the reported sex pheromone of European corn borer and redbanded leafroller moths. However, geometrically pure preparations of the compound are weakly attractive to these species. Presence of the E geometrical isomer in the Z is necessary for maximum sex attraction and these moths are "tuned" to respond optimally to specific proportions of Z to E. This discovery is important to considerations of moth pheromonal specificity, evolution, and in application of knowledge of the pheromones to insect-pest suppression.