Total Synthesis of Peniphenones A-D via Biomimetic Reactions of a Common o-Quinone Methide Intermediate

The total synthesis of peniphenones A-D has been achieved via Michael reactions between appropriate nucleophiles and a common o-quinone methide intermediate. This strategy, which was based on a biosynthetic hypothesis, minimized the use of protecting groups and thus facilitated concise syntheses of the natural products. The most complex target, the benzannulated spiroketal peniphenone A, was synthesized enantioselectively in nine linear steps from commercially available starting materials.