Total Syntheses of Squamocin A and Squamocin D, Bi-tetrahydrofuran Acetogenins from Annonaceae

The total syntheses of the Annonaceous acetogenins squamocin A and squamocin D have been achieved. The synthesis follows a modular strategy, wherein a left-side chain, the central bis-THF core and the right-side chain are assembled together. Key reactions are additions of organomagnesium compounds to bi-THF aldehydes. At the end of the synthesis the butenolide moiety was introduced. This modular synthetic approach should be useful for the synthesis of other related natural products as well as pharmacologically interesting analogs.