Total synthesis of (-)-Penifulvin A, an insecticide with a dioxafenestrane skeleton.
Herein we report the first total synthesis of Penifulvin A, a sesquiterpenoid with a novel dioxa-fenestrane structure. Penifulvin A is a potent insecticide against the fall armyworm Spodoptera frugiperda which causes enormous damage in the US by consuming foliage of a variety of field crops. A five-step racemic and an eight-step enantioselective route to the natural product and the determination of its absolute configuration are described. The key step involves a meta-photocycloaddition, giving rapid access to the carbon skeleton of penifulvin A in a stereoselective fashion. Finally an oxidation cascade leads to the natural product. The synthetic route is free from protecting groups, scalable, and flexible so that a variety of analogues, among them penifulvins B-E, should be available for performing SAR tests in the insecticidal role.
Gaich
Tanja
T
University of Vienna, Institute of Organic Chemistry, Wahringer Strasse 38, 1090 Wien, Austria. tanja.gaich@univie.ac.at
Mulzer
Johann
J
D000085:Acetates / Q000737:chemistry; D003500:Cyclization; D007306:Insecticides / Q000138:chemical synthesis*; D055668:Photochemical Processes; D012717:Sesquiterpenes / Q000138:chemical synthesis*; D013237:Stereoisomerism; D014050:Toluene / Q000031:analogs & derivatives
D000085:Acetates; D007306:Insecticides; D012717:Sesquiterpenes; C515096:penifulvin A; D014050:Toluene