Opop

Figure 6.23 The biosynthesis of homomevalonate from acetate (as malonate) and propionate units. The black dot on carbon indicates a labelled carbon of propionate. Isomerization of 3-methylenepentyl pyrophosphate gives rise to three possible kinds of branching. The one shown on the left is most common and the formation from it of a homosesquiterpene is illustrated homofarnesene bishomofarnesene trishomofarnesene

Figure 6.24 Homologues of farnesene found in Myrmica ants, containing one, two or three homomevalonate units replacing mevalonate

Figure 6.24 Homologues of farnesene found in Myrmica ants, containing one, two or three homomevalonate units replacing mevalonate

H/\ homohimachalene

Figure 6.25 Further examples of homosesquiterpenes from insects. Faranal has two homomevalonate units, homohimachalene has one units incorporated in different ways. Homohimachalene (Figure 6.25) is the sex pheromone of the sandfly Lutzomyia longipalpis one of the species which carries the protozoal disease Leishmaniasis in South America.

Figure 6.26 Some homomonoterpenes. Compounds a and b, decyl and dodeeyl esters of 4-methylgeraniol, form the trailpheromone of the ant Gnamptogenys striatula, compound c, a bishomomonoterpene is also present in the gland mixture but does not contribute much to the pheromone blend. These compounds come from the Dufour gland

Figure 6.26 Some homomonoterpenes. Compounds a and b, decyl and dodeeyl esters of 4-methylgeraniol, form the trailpheromone of the ant Gnamptogenys striatula, compound c, a bishomomonoterpene is also present in the gland mixture but does not contribute much to the pheromone blend. These compounds come from the Dufour gland

The first homomonoterpene and bishomomonoterpene have recently been discovered. A mixture of decanoate and dodecanoate of the third form of homogeranyl pyrophosphate shown in Figure 6.22, (4S,2E)~ 3,4,7-trimethyl-2,6-octadienol (Figure 6.26) have been found to be the trail pheromone of the ponerine ant Gnamptogenys striatula. The dodecanoate of the bishomomonoterpene (45',2£',6J£)-3,4,7-trimethyl-2,6-nonadienol was also present but only marginally active in the pheromone.

0 0

Post a comment