Total synthesis of (±)-przewalskin B.

A concise total synthesis of przewalskin B was accomplished from readily available diene 7. Key features of the synthesis involved a Diels-Alder reaction to install the A ring, a Claisen-Johnson rearrangement to establish the spiroquaternary center, and a ring-closing metathesis (RCM) of a sterically crowded system to construct the cyclic enone moiety.