POLYAZAMACROLIDES FROM LADYBIRD BEETLES - RING-SIZE SELECTIVE OLIGOMERIZATION

The pupal defensive secretion of the 24-pointed ladybird beetle, Subco ccinella vigintiquatuor punctata, consists of a mixture of macrocyclic polyamines, dominated by the three dimeric, 30-membered macrocycles 1 1-13, derived from the two building blocks 11-(2-hydoxyethylamino)-5-t etradecenoic acid (9) and 11-(2-hydoxgethylamino)-5,8-tetradecadienoic acid (10). Smaller amounts of the four possible cyclic trimers of 9 a nd 10 were also detected, corresponding to 45-membered macrocycles. St ructural assignments were based on NMR-spectroscopic investigations an d HPLC-MS analyses. In addition, the all-S absolute configuration of t he S. vigintiquatuor punctata macrocycles was determined by comparison of derivatives of the natural material with enantiomerically pure syn thetic samples. Comparing this alkaloid mixture with that of the pupal defensive secretion in related ladybird beetle species indicates that the degree of oligomerization of the 2-hydroxyethylamino carboxylic a cid building blocks can be carefully controlled by the insects.