Fragmentation of Homoallylic Alkoxides. Thermolysis of potassium 2‐substituted bicyclo [2.2.2]oct‐5‐en‐2‐alkoxides

Thermolysis of the potassium 2‐substituted bicyclo [2.2.2]oct‐5‐en‐2‐alkoxides derived from alcohols 2–17 at 90–120° in hexamethylphosphoric triamide affords unsaturated ketones resulting from allylic bond cleavage. The mechanistic and synthetic aspects of this anionic fragmentation are discussed with reference to the formation of 1‐(3′‐cyclohexenyl)‐2‐alkanones 18–28 via initial heterolytic C(1), C(2)‐bond cleavage in the substrate alkoxide and regioselective, intramolecular protonation of the resultant transient allylic anion.