2,6 -Dodecadienal

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. 

Not many trail pheromones of termites have been identified, but one group is worth mentioning here. In the group Macrotermitinae, for some species (Z)-3-dodecan-l-ol is the trail pheromone, while for another (Z,Zj-3,6-dodecadien-l-ol is. In both cases the sternal gland is the source. It is suggested that these alcohols are formed from oleic acid and linoleic acids, respectively, by loss of three acetate units and reduction to the alcohol (Figure 3.31). 

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... 

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. 

However, this behavior cannot be depended on. It is safer to monitor hydrogen uptake. Reduction of 4-oxo-slowed down at the ethylene stage although in other compounds, the same catalyst did give spontaneously selective reductions. 

Farnesyl, 10-bromo-10,l 1-dihydro-l 1-hydroxy-, acetate [2,6-Dodecadiene-1,11-diol, 10-bromo-3,7,11-trimethyl-, 1-acetate, ( , )-], 113 Ferrocene, 28... 

Aus 2-Methyl-dodecadiin-(3,5) erhalt man mit zwei Mol-Aquivalenten Dicyclohexyl-boran und Protonolyse 2-Methyl-cis,cis-dodecadien-(3,5)2 (74% d.Th. Kp3 80°). (Wei-teres iiber die Reaktion s.ds. Handb., Bd. V/lb, S. 799ff.) ... 

Comparative GC, GC-EAD and GC-MS analyses of extracted Setora nitens (nettle caterpillars) compounds and authentic standards showed that the candidate pheromone components were ( )-9-dodecenal and (-Z)-9,11 dodecadienal. The other two EAD-active compounds were the corresponding alcohols of these aldehydes. ... 

Finally, a Japanese group also studied the biotransformation of Z- and -nerolidol [137,138] with the plant pathogenic fungus Glomerella cingulata. Both Z- and -nerolidol were mainly oxidised at the remote double bond. Z-Nerolidol (162) was transformed into (Z)-3,7,11-trimethyl-l,6-dodecadiene-3,10,11-triol (164) while -nerolidoI (158) was mainly oxidised to ( )-3,7,11-trimethyl-l,6-dodecadiene-3,ll-diol (171) only small amounts of ( )-3,7,11-trimethyl-l,6-dodecadiene-3,10,11-triol (160) were obtained, Fig. (34). 

More recently, the biotransformation of (2 ,6 )-famesol (181a) was also carried out by a Japanese group [141] using the fungus Glomerella cingulata. At the first step, oxidation proceeded at the remote double bond to give (2.E,6 )-3,7,11 -trimethyl-2,6-dodecadien-l,l 1-diol (184) and (22 , 6E)-3,7,11 -trimethyl-2,6-dodecadien-l,10,ll-triol (185). In the second step, the diol (184) was further hydroxylated to (22 ,62s)-3,7,ll-trimethyl-2,6-dodecadien-l,5,ll-triol (186), which was further isomerised to its (2Z,6 )-isomer (187), Fig. (36). 

Butene 4-Cyclohexyl-2-ethoxy-1.1,1-trifluoro- ElOb, 459 (F3C-COOR + -CH2-R) 2,4-Dodecadiene 12-Hydroxy-l,l,l-trifluoro- E10b2, 176f. (2-In —> 2,4-Dien)... 

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