PROGRESS TOWARDS THE SYNTHESIS OF TYPE B POLYCYCLIC POLYPRENYLATED ACYLPHLOROGLUCINOL 7-epi-CLUSIANONE

Plants of the family Guttiferae produce polycyclic polyprenylated acylphloroglucinols (PPAPs), which have interesting biological activities including anticancer and antibacterial properties. The main structural features of PPAPs comprise of bicyclo[3.3.1]nonane-2,4,9-triketone with one acyl group together with prenyl, geranyl, or other C10H17 groups. 7-epi-Clusianone, a type B PPAP with C-7 endo stereochemistry, is being approached by establishing the cis relationship with C(4) allyl group and C(2) methyl ester in the early stage of the synthesis. Then C(2) methyl ester is converted to alkyne aldehyde and syn reduction followed by intramolecular aldol reaction to give bicyclo[3.3.1]nonane structure with C(7) endo stereo chemistry