A Kinetic Study of the Conjugate Addition of Benzenethiol to Cyclic Enones Catalyzed by a Nonsymmetrical Uranyl−Salophen Complex

The Et3N-assisted addition of benzenethiol to enones in chloroform is catalyzed with high turnover efficiency by the phenyl-substituted uranyl-salophen compound 3. Catalytic data show a close adherence to a quatermolecular mechanism involving reaction of a base-activated thiol with a reversibly formed complex of enone and metal catalyst, with a complication of product inhibition due to the formation of a product-catalyst complex. The role of the binding energy made available by interactions with the aromatic sidearm of the catalyst is discussed in terms of catalyst-substrate and catalyst-transition state complementarity.