Synthesis of the 5/6 fused-spiro tricyclic framework of manginoid A

Abstract

We developed a concise, ten-step route to the 5/6 fused-spiro tricyclic framework (A/B/C rings) of manginoid A from the starting materials cyclopentenone and 1,3-cyclohexanedione. Michael addition and subsequent Mukaiyama aldol reaction introduced two side chains at the α,β-positions of cyclopentenone. Tsuji–Trost allylation of this cyclopentenone moiety and 1,3-cyclohexanedione afforded a key intermediate. A late-stage Michael addition formed the spiro-fused tricyclic framework.