Synthesis of unsaturated polyazamacrolides from the ladybird beetle Subcoccinella vigintiquatuorpunctata

The pupal defensive secretion of the ladybird beetle Subcoccinella vigintiquatuorpunctata consists of a mixture of macrocyclic polyamines (polyazamacrolides, PAMLs) dominated by three dimeric, 30-membered bislactones (1, 2, and 3), which represent the three possible head-to-tail combinations of the two building blocks (S)-(Z)-11-(2-hydroxyethylamino)-5-tetradecenoic acid (4) and (S)-(5Z,8Z)-11-(2-hydroxyethylamino)-5,8-tetradecadienoic acid (5). We now report the synthesis of these three alkaloids via a route involving the nucleophilic opening of a chiral aziridine as a common step.