Sustainable Heck-Matsuda Reaction with Catalytic Amounts of Diazonium Salts: An Experimental and Theoretical Study

The palladium‐catalyzed Heck–Matsuda reaction with a catalytic amount of an in‐situ‐generated diazonium salt proceeded under mild and sustainable conditions. The reaction proceeded at room temperature, under base‐free conditions, and only generated tBuOH, H2O, and N2 as by‐products. Ortho‐substituted diazonium salts were more‐efficiently coupled to methyl acrylate than their corresponding para isomers, which required the addition of anisole as an additive. In support of these experimental data, we carried out theoretical studies to gain a deeper understanding of these reaction outcomes. Flipping Heck: An investigation into the mechanism of the Heck–Matsuda reaction with a catalytic amount of diazonium salt found that a coordinating group or an additive was required to stabilize the Pd complex formed during the oxidative addition (see figure).