RuH‐Catalyzed Synthesis of 1,3‐Diaryl Ketones via Cross‐Coupling of Aromatic Enones with Aromatic Aldehydes and Mechanistic Insights

Abstract RuHCl(CO)(PPh 3 ) 3 ‐catalyzed cross‐coupling of alkenyl ketones with aldehydes has been extended to the synthesis of 1,3‐diaryl 1,3‐diketones. The reaction has been successfully applied to the synthesis of PPT (propyl pyrazole triol), a selective estrogen receptor modulator compound. A study of the stoichiometric reaction of phenyl vinyl ketone with RuHCl(CO)(PPh 3 ) 3 has revealed that the β‐ruthenium ketone PhCOCH 2 CH 2 RuCl(CO)(PPh 3 ) 2 , a five‐membered ruthenacycle is formed with liberation of one molecule of PPh 3 . The observed catalytic activity of this ruthenacycle in the presence of PPh 3 suggests that it serves as a resting state, in equilibrium with an oxa‐π‐allyl ruthenium species, which is the key coupling partner with aldehyde substrates. magnified image