2.3- Dodecadiene, preparation

Complex formation provides a simple meahod for purifying straight-chain a,M> dienes containing 12 or more carbon atoms. Dodecadiene prepared according... 

The preparation of the sex pheromone of the bollworm moth, ( )-9,ll-dodecadien-l-yl acetate, from compound A has been described. Suggest suitable reagents for each step in this sequence. 

B. (E)-7,11-Dimethyl-6,10-dodecadien-2-yn-1-ol. To the suspension containing the acetylide intermediate 2, as prepared in part A, is added 14 g (460 mmol) of paraformaldehyde (Note 12) in portions (Note 13) over 10 min (Note 14). After stirrinj the mixture for 24 hr, the resulting suspension is poured into 450 mL of ice-cold watei (Note 15), the aqueous layer is saturated with sodium chloride, and the product is extracted with four 100-mL portions of ether. The combined organic extracts are dried over magnesium sulfate, the drying agent is removed by filtration, and the solvent is removed at room temperature on a rotary evaporator. The residue is distilled through a short-path distillation apparatus to provide a forerun of 2-butyn-1 -ol (bp 42-46°C, 6 mm), followed by 10.5 g (68% yield) of (E)-7,11 -dimethyl-6,10-dodecadien-2-yn-1-ol as a colorless liquid, bp 120-124°C (0.5 mm) (Note 16). 

Acetoxy-l,ll-dodecadien-3-one (17) is a synthetic equivalent of 1-dodecene-3,7,11-trione (18), and prepared from l,7-octadien-3-one (16), which is obtained from the butadiene telomer 15 (see Section 5.2). The acetoxy group and the double bond in 17 are precursors of two carbonyl groups. The reagent 17 is used for steroid synthesis. 

By an analogous cuprous bromide-methyl sulfide catalyzed procedure for the synthesis of (E, )-dienes conjugated (Z, Z)-dienes can also be prepared by substituting the initial alkyne with 1-halo-l-alkyne. For example, (5Z, 7Z)-5,7-dodecadiene is prepared in 85% yield in high stereochemical purity (Eq. 91)144). 

Subsequently the trisanellation reagent, 7-acetoxy-l,ll-dodecadien-3-one 0M>) was prepared from the bisanellation reagent (67), and the synthesis of D-homo-19-norandrosta-4-en-3-one (82) was carried out from (79) as shown below. For the A-ring formation, the unmasking of the termi double bond and hydrogenation afforded the 1,5-diketone (81), which was subjected to intramolecular aldol condensation to give D-homo-4-androstene-3,17a-dione (82 Scheme 23). 

Anion (64) generally reacts with carbonyl compounds at the y-position, whereas it reacts with alkyl halides at the a-position. The triethylaluminum ate complex of (64) exhibits reversed regioselectivity propanal and 2-methylpropanal give exclusively the a-adducts. The anti isomers are produced predominantly. Organic halides and trimethylsilyl chloride do not react with the aluminum ate complex. 9,11-Dodecadien-l-yl acetate, a pheromone of Diparopsis castanea, is prepared by condensation of 9-oxonon-l-yl acetate via the ate complex (Scheme 43). 

Thexylborane in tetrahydrofuran added dropwise at 0° to a soln. of 1-hexyne in the same solvent, stirred an additional hr. at 0-5°, the resulting vinylborane soln. treated with solid trimethylamine oxide at sudi a rate that the temp, remains between 0 and 5°, stirred an additional hr. at this temp., 3 N NaOH added followed by dropwise addition of iodine in tetrahydrofuran -> cis,trans-S,l-dodecadiene. Y 65%. cw,cw-Isomers can be prepared with diisobutylaluminum hydride. F. e. s. G. Zweifel, N. L. Polston, and C. C. Whitney, Am. Soc. 90, 6243 (1968). 

If cyclooctene conversion achieved 93%, a mixture of 1,9-dodecadiene had 7JE stereocontent 50/50. We have used this mixture for preparation of accurate copies of natural pheromones of cherry bark tortix moth (Enarmonia formasana) according to the Scheme 3. 

The Pd-catalyzed elimination reaction was applied to the synthesis of 12-acetoxy-l,3-dodecadiene, an insect sex pheromone from the red bollworm moth, by elimination of phenol with Pd(OAc)2 and P(OPh)3 at 160 °C under reduced pressure (1 torr) from the allyl phenyl ether prepared from a butadiene telomer (Scheme... 

In our poster presentation earlier in this conference we reported finding dodecenyl alcohol and tetradecenyl alcohol in four varieties of untreated apples at concentrations ranging from 70-130 ppb. The natural occurrence of these compounds in apples had been reported in 1976, but not quantitated (5). The irony is that they are two of the five components in an experimental lepidopteran insect sex pheromone for which residue determinations were made of all components on treated apples. This full season application included 52 g/ha and 10 g/ha of dodecenyl alcohol and tetradecenyl alcohol, respectively. These were minor constituents, the major component was 106 g/ha of E,E-8,10-dodecadien-l-ol. No increased levels of the saturated alcohols were detected in fruit from treated orchards, and none of the latter, major component, was detectable above 10 ppb, our level of sensitivity (Spittler, T. D., Leichtweis, H. C. and Kirsch, P. Manuscript in preparation). 

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