α‐Arylation and Ring Expansion of Annulated Cyclobutanones: Stereoselective Synthesis of Functionalized Tetralones

α‐Arylcyclobutanones display unique reactivity that makes them valuable synthetic intermediates and target molecules. We describe the preparation of α‐aryl‐ and α‐heteroarylcyclobutanones through a direct α‐arylation reaction. Problematic fragmentations are avoided by the use of LiO^tBu, which promotes a rapid but reversible self‐aldol reaction that slowly releases the enolate required for α‐arylation. We also demonstrate the ring expansion of α‐arylcyclobutanones, a process that is highlighted in the stereoselective synthesis of 1‐methoxy coniothyrinone D.