Synthesis of (+)-Awajanomycin

Significance

Awajanomycin was isolated from the marine sponge Acremonium sp. AWA16-1 and has shown high levels of cytotoxicity in experiments with A549 cells. Its unique γ-lactone/δ-lactam core structure makes the molecule a synthetically challenging target, with one total synthesis and two approaches to the bicyclic core reported. This synthesis features a novel enantioselective ­allylboration with a vic-tricarbonyl reagent to set the stereochemistry of the core and the synthesis was completed in eleven steps from A with 16% overall yield.