Structural Revision and Biomimetic Synthesis of Goupiolone B.

Goupiolones A and B are unique phenolic compounds with significant DNA-damaging activity. In this study, the structure of goupiolone B was revised on the basis of DFT calculations of the 13 C NMR chemical shifts and biosynthetic considerations. The dibenzobicyclo[3.2.2]nonane skeleton of the revised structure suggested that goupiolone B was produced by oxidative coupling between catechol and goupiolone A, which was strongly supported by biomimetic synthesis. Furthermore, racemization of goupiolone B was observed during the attempted resolution of its racemic mixture. A plausible racemization mechanism involving α-ketol rearrangement is proposed.