Platinum‐Catalyzed α,β‐Desaturation of Cyclic Ketones through Direct Metal–Enolate Formation

The development of a platinum‐catalyzed desaturation of cyclic ketones to their conjugated α,β‐unsaturated counterparts is reported in this full article. A unique diene‐platinum complex was identified to be an efficient catalyst, which enables direct metal‐enolate formation. The reaction operates under mild conditions without using strong bases or acids. Good to excellent yields can be achieved for diverse and complex scaffolds. A wide range of functional groups, including those sensitive to acids, bases/nucleophiles, or palladium species, are tolerated, which represents a distinct feature from other known desaturation methods. Mechanistically, this platinum catalysis exhibits a fast and reversible α‐deprotonation followed by a rate‐determining β‐hydrogen elimination process, which is different from the prior Pd‐catalyzed desaturation method. Promising preliminary enantioselective desaturation using a chiral‐diene‐platinum complex has also been obtained.