Resumen de Iterative synthetic strategy to azaphenalene alkaloids. Total synthesis of (-)-9a-epi-hippocasina
Ladybugs belong to Coccinelidae family. Most of these species eat aphids and mites, which are especially damaging for several kinds of crops. Taking advantage of this fact, there are some approaches where Coccinellidae family insects are used as biological control of agricultural pests. Ladybugs protect themselves against predators by its coloration, especially when they form aggregations. Reflex bleeding is another known method of protection; it consists in an orange fluid secretion, which has a bitter taste. From this fluid, several alkaloids have been isolated. An example of these are azaphenalene alkaloids, which are a family of compounds presenting a common feature based on perhydro-9b-azaphenalene. Until now, there are only two published syntheses of these alkaloids in enantiopure form.
In this thesis, the enantioselective total synthesis of the non-natural alkaloid (-)-9a-epi-hippocasine is described. An iterative strategy has been developed, where the key steps are a palladium catalyzed asymmetric allylic alkylation reaction of glutarimide, two diastereoselective nucleophilic allylation reactions and two ring closing metathesis processes.
Further studies directed to the synthesis of other members of this alkaloids family were also undertaken.
