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

Abstract

The development of aplatinum-catalyzed desaturation of cyclic ketones to their conjugated a,b-unsaturated counterparts is reported in this full article.Aunique dieneplatinum 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.Awide range of functional groups,i ncluding those sensitive to acids,b ases/nucleophiles,o rp alladium species,a re tolerated, whichr epresents ad istinct feature from other knownd esaturation methods.M echanistically,t his platinum catalysis exhibits af ast and reversible a-deprotonation followed by ar ate-determining b-hydrogen elimination process,w hich is different from the prior Pd-catalyzed desaturation method. Promising preliminary enantioselective desaturation using ac hiral-diene-platinum complex has also been obtained. Scheme 1. Pd and Pt-catalyzed desaturation of carbonyl compounds.