Sex pheromone components of female German cockroach

105 and 1.9 x 10-6M for 106. In other words, 105 was about 10 times more active than 104, while 106 was about twice as active as 104. Synthesis of all the four stereoisomers of 104 as well as those of 105 by us in 1981 allowed us to establish the absolute configuration of 104 and 105 as 35,115.101,102 

Let me first explain the manner by which we determined the absolute configuration of 104 as 35,US .101,102 At the time of the structure determination of 104, Nishida et al. proposed the 35-configuration on the basis of its ORD (optical rotatory dispersion) spectrum coupled with NMR studies employing a chiral shift reagent. No information was available to assign the absolute configuration at C-ll, 

Their optical rotations and melting points (Table 4.1) were very important in assigning the absolute configuration of the natural pheromone. The natural ketone 104 was dextrorotatory in hexane, and (35,115)-104 as well as (35,115)-104 showed positive rotations, while (3R,11R)- and (35,115 )-104 were levorotatory. 

The natural 104 must therefore be either (35,115)- or (35,ll/ )-104. All the stereoisomers of 104 showed IR spectra (as chloroform solutions) identical to each other. When their IR spectra were measured as nujol mulls, the stereoisomeric and crystalline ketones showed small differences in the spectra due to the differences in their crystal structures. Thus, the natural 104 showed a IR spectrum identical to those of 

To support this conclusion, melting points (mps) of the four stereoisomers of 104 were measured, and the mixture mp determination of the four isomers with the natural 104 were executed. As can be seen from Table 4.1, (35,115)- and (3/ ,ll/ )-104 showed the same mp as that of the natural 104. Mixture mp determinations revealed (35,115)-104 to be the natural pheromone, because it showed no mp depression. The classical method of mixture mp test was still useful in establishing the identity of two like samples. Similarly, the absolute configuration of the natural 105 could be established as 35,115, too.102 In analogy with 104 and 105, all the remaining pheromone components 106-109 are assumed to possess 35,115 configuration due to the same biosynthetic origin. 

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