Mechanistic and Kinetic Studies of Reductions of α,β Unsaturated Esters and Ketones by SmI ₂ –Water

The coupling of ketones with activated olefins is an important class of reactions that has been widely proposed to undergo initial reduction of the ketone, followed by radical addition of the intermediate ketyl to the olefin. In an initial study, we examined the rate of reduction of several α,β unsaturated esters and cyclic ketones by SmI₂-water. These studies demonstrate that the rate of reduction of the activated olefin is substantially faster than that of the ketones examined. We also uncovered an unusual rate order dependence for water in the reduction of α,β unsaturated esters.