Radical-Polar Crossover Catalysis with a d0 Metal Enabled by a Redox-Active Ligand

Radical-polar crossover mechanisms are invoked in numerous late transition metal and photocatalyzed reactions. To the best of our knowledge, reductive radical-polar crossover mechanisms are not invoked for group 3 early transition metals due to their propensity to exist in high oxidation states. Through use of a redox-active (tris)amido ligand we have accessed this mechanism for use with early transition metals. This mechanism is showcased through enabling product formation for a wide variety of elimination products from -halo substituted benzylic bromides. The mechanism of this new type of reactivi-ty with Sc is explored and Hammett analysis reveals an anionic intermediate. The wide functional group tolerance of this reaction is also demonstrated.