Asymmetric total synthesis of naturally occurring spirocyclic tetranorsesquiterpenoid lanceolactone A.

Asymmetric total synthesis of naturally occurring gamma-butenolide containing [4.4]spiro-tetrahydrofuran lanceolactone A has been reported in the present work. Bimetallic ("Pd-Cu") cascade cyclization was the crucial reaction employed for the construction of the gamma-butenolide framework of the natural product. Subsequently, iodocyclization and reductive deiodination through a transfer hydrogenation reaction were applied to access the target molecule in an efficient manner.