Organic and Inorganic Chemistry

Annonaceous acetogenins are a group of natural products that have been isolated from different species of the Annonaceae plant family.1 Uvaricin was the first Annonaceous acetogenin isolated (1982) from roots of Uvaria accuminata and was fully characterised.2 The great interest in acetogenins was initiated from the biological activity of uvaricin against P-388 lymphocytic leukaemia in mice.3 This significant discovery led to the isolation of more than 450 acetogenins since 1982.4 Diepomuricanin A (syn and anti forms), are bis-epoxy acetogenins and was isolated from the seeds, roots and stem barks of Annona muricata in 1992 by Cavé’s group.5,6 Additionally, it has been isolated from the seeds of Rollina membrancea and leaves of Rollina Ulei.5 Natural diepomuricanin A (1) was later found to be a mixture of syn-diepomuricanin A (syn-1a) and anti-diepomuricanin A (anti-1b) in 1:1 ratio (Figure Error! No text of specified style in document.).5 However, the absolute stereochemistry remains undetermined. In order to identify the absolute stereochemistry of the natural product diepomuricanin A (1), we designed a synthetic route for the synthesis of the four possible stereoisomers (1a-d). We believed that HPLC comparison of the synthetic diastereoisomers with the natural product would then allow the stereoisomers of the natural product to be defined.