Synthesis of yomogin using a telescoped α-methylene-γ-butyrolactone annelation procedure

A novel and efficient synthetic route to the anti-cancer natural product yomogin has been developed using a Telescoped Intramolecular Michael-Olefination (TIMO) sequence as the key step. Two variants of the TIMO sequence have been used successfully: a two-step acylation approach using diethyl phosphonoacetic acid and a base-free variant using triphenylphosphoranylideneketene (Bestmann’s ylide). The natural product, 3-oxodiplophyllin, was also prepared en route to yomogin.