Total syntheses of squamocin A and squamocin D, bi-tetrahydrofuran acetogenins from Annonaceae

The total syntheses of the Annonaceous acetogenins squamocin A and squamoci n 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 ass embled together. Key reactions are additions of organomagnesium compounds t o bi-THF aldehydes. At the end of the synthesis the butenolide moiety was i ntroduced. This modular synthetic approach should be useful for the synthes is of other related natural products as well as pharmacologically interesti ng analogs.