A Total Synthesis of (±)‐9‐Pupukeanone

A stereoselective total synthesis of (±)‐9‐pupukeanone (3), an intermediate employed in previously reported total syntheses of the structurally novel sesquiterpenoid (±)‐9‐isocyanopupukeanane (1), is described. In the key step of the synthetic sequence, the epimeric mixture of allylic alcohols 15, obtained in 7 steps from 4,6‐dimethyl‐1,3‐cyclohexanedione (6), underwent a smooth intramolecular Diels‐Alder reaction, providing in high yield the tricyclic alcohols 18 (mixture of epimers). The latter material was converted via a 5‐step sequence into (±)‐9‐pupukeanone (3).