frans-solenopsin A


N,2-dimethyl-6-alkylpiperidines n =8 or 10

Figure 9.5 2-Methyl-6-alkylpiperidines and tetrahydropyridines and some N-methyl derivatives found in the venom o/Solenopsis fire ants. The two solenopsins A form almost the total venom of S. geminata

[2-14C]-acetate, followed by dilution with 'cold' synthetic 2-methyl-6-undecylpiperidine indicated that the compounds are biosynthesized as shown in Figure 9.6. As a first estimate, the pathway seems similar to that of coniine in plants. The synthesis begins with the linking together of 9, 10 or 11 acetate units. It is not clear whether this is through a fatty acid or a polyketide. At some stage a keto-acid must be formed, which is decar-boxylated; addition of an amino-group, cyclization and (for most of the compounds) reduction gives the solenopsins.

Another group of Solenopsis (thief ants) and some species of Mono-morium ants have alkyl-pyrrolidines and -pyrrolines (Figure 9.7). The sting of these ants does not seem to be so painful, but whether this is due to the alkaloids or the protein part of the sting is not known. More recently some of the same and similar pyrrolidines have been found in Megalomyrmex ants. Their biosynthesis is not yet known.


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