9,11 -Dodecadien synthesis

The trisannulation reagent 7-acetoxy-l,l l-dodecadien-3-one (134) is derived from the bisannulation reagent 124 in four steps. This reagent is a synthetic equivalent of l-dodecene-3,7,11-trione, and the two ketone groups of the trione are masked as an acetoxy and a terminal alkene. The synthesis of optically active D-homo-19-norandrosta-4-en-3-one (135) by the trisannulation reaction... 

Recent trend in the synthesis of olefinic pheromones is the use of transition metal-catalyzed cross coupling reaction for carbon-carbon bond formation. Scheme 8 summarizes a synthesis of the termite trail marker pheromone, (3Z,6Z)-3,6-dodecadien- l-ol (2) by Oehlschlager [19]. The key-step is the palladium-catalyzed cross-coupling of allylic chloride A and alkenylalane B. 

PROPARGYLATION OF ALKYL HALIDES SYNTHESIS OF (E)-6,10-DIMETHYL-5,9-UNDECADIEN-1-YNE AND (E)-7,11-DIMETHYL-6,10-DODECADIEN-2-YN-1-OL... 

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. 

PROPARGYLATION OF ALKYL HALIDES SYNTHESIS OF (E)-6,10-DIMETHYL-5,9-UNDECADIEN-1-YNE AND (E)-7,11-DIM ETHYL-6,10-DODECADIEN-2-YN-1-OL (5,9-Undecadien-1-yne, 6,10-dimethyl-, (E)-) and (6,10-Dodecadien-2-yn-i-ol, 7,11-dimethyl-, (E)-)... 

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). 

Many insect pheromones have conjugated cis, trans-diene system l52, l53). The versatility of these reactions is exemplified in the synthesis of many natural products l53-154, 55 In Eq. 99, the four step synthesis of a natural sex pheromone of the European grape vine moth (Lobesia botrana), (7E, 9Z)-7,9-dodecadien-l-yl acetate, is illustrated 155). 

Recently, Rossi et al. have applied the cross-coupling of 1-alkenylboranes with 1-alkynyl halides for the synthesis of natural products. Thus, (7 , 9Z)-7,9-dodecadien-1-yl acetate (32), the sex pheromone of Lobesia botrana, has been synthesized by the following sequence involving ... 

The importance of these reactions is exemplified in the synthesis of (5Z, 1E)-5,1-dodecadien-l-ol (Eq. 113), a sex pheromone component of the forest tent catapillar... 

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). 

This new coupling procedure was used in a recent stereoselective synthesis of a sex attractant of the codling moth, leans,trans-i, 10-dodecadiene-1 -ol(4).2 Thus coupling of (1) with (2) catalyzed by dilithium tetrachlorocuprate gave (3) in 85 % yield. This product consisted of 78 % of the desired trans,trans-isomer. Hydrolysis of the protective group (p-TsOH in aqueous methanol) gave the free alcohol (4) containing about 80% of the desired tains,(row-alcohol. The pure alcohol (4) was obtained by crystallization from pentane at - 5°. 

The theimolysis of 2-substituted 2,5-dihydrothiophene 1,1-dioxides leads to ( ) conjugated dienes via cycloieversion followed by the concerted cheletropic extrusion of sulfur dioxide. The thermolysis of the a, -alkylated sulfone (96) gives the intennediate, which loses SO2 to give 1-dodecadien-l-yl acetate (98), a component of the sex pheromone of the red bollwoim moth. Tliis procediue has been extended to the thermolysis of a,3-dialkylated sulfones in order to obtain ( , )-1,4-disubstituted-1,3-dienes (equation 46). Similar processes have been used for the syntheses of alkaloids. The synthesis of an Elaeocarpus alkaloid, elaeokwine A (100), makes use of the retrodiene extrusion of sulfur dioxide to give the 1,3-diene intermediate (99) that is subsequently consumed by an intramolecular imino DA reaction (equation 47). o-Xylylene (102) has been generated by rDA expulsion of SO2 from benzo-fiised 3,6-dihy(ho-l,2-oxathiin 2-oxide (101). ... 

Recognition of possible synthons in a target molecule is the most important factor to make its synthesis simple or complicated. Let us compare the efficiency and simplicity of three different syntheses of (8 ,10 )-8,10-dodecadien-l-ol (11), the female-produced sex pheromone of the codling moth, Cydia pomonella. This moth is a notorious pest of apple orchards. 

Using enantiomerically pure 4-hydroxy-2-alkynoate and 1,11-dodecadiene with CpRu(cod)Cl as catalyst, this reaction type was used in the synthesis of the acetogenin (+)-ancepsenolide, a bisbutenolide with a 12-carbon chain linking both lactone units "4. The primary addition step of this conversion represents an example of a ruthenium-catalyzed Alder-ene reaction (vide infra). Other examples of this type have been reported123. 

Root extracts of the American coneflower, Echinacea augustifolia DC., also exhibited juvenoid activity [114] ether extracts showed high morphogenic activity on T. molitor pupae but none was observed on fifth instar nymphs of O. fasciatus (500 ig of extract). The active principle in the oil was identified as ( )-10-hydroxy-4,10-dimethy 1-4,11-dodecadien-2-one or echinolone (Fig. (6)) [109]. However, chemically synthesized echinolone was not active in the standard T. molitor pupal bioassay [115]. The authors of this report acknowledge that this may be due to a failure to synthesize the proper compound. However, the spectral data is consistent with that reported. They were also unable to isolate echinolone from the roots of E. augustifolia. The chemical data for echinolone are summarized in Appendix III, Table 12 and the synthesis of racemic echinolone has been reported [115, 116]. 

Dienes biaryls. Vinylmercuric chlorides can be dimerized to 1,3-dienes by stoichiometric amounts of palladium(II) chloride and lithium chloride (Lia-PdCU) . More recently, this reaction has been improved by use of this rhodium(I) complex in combination with lithium chloride. This system can function in catalytic amounts. RhCls and LiCl ate somewhat less effective. An example is the synthesis of /ranj,tranj-5,7-dodecadiene (equation I). ... 

Dienes. Negishi and Abramovitch have found that reasonably hindered organoboranes are much more reactive to alkynyllithiums than an acetoxyl group is and have used this property for an efficient synthesis of (7E, 9Z)-dodecadien-1 -yl acetate, a sex pheromone of the European grapevine moth (equation I). 

---