A Thermally Stable, Alkene-Free Palladium Source for Oxidative Addition Complex Formation and High-Turnover Catalysis

Abstract

Oxidative addition complexes play a crucial role in Pd-catalyzed transformations. They are not only key catalytic intermediates but also powerful and robust precatalysts, and effective reactants for late-stage functionalization of complex molecules. However, accessing a given oxidative addition complex is often challenging due to a lack of effective and stable palladium sources with the correct reactivity. Herein, we report an easily prepared and bench-stable Pd(II) dialkyl complex, DMP DAB–Pd–BTSM ( DMP DAB = N, N ′-bis(2,6- d i m ethyl p henyl) d i a za b utadiene; BTSM = b is( t rimethyl s ilyl m ethyl)), that is a versatile precursor for generating Pd(II) oxidative addition complexes and is highly active as a Pd source for in situ catalyst formation in cross-coupling reactions. A crucial aspect of this structure is the absence of alkene-based stabilizing ligands common to other Pd precursors. We demonstrate the utility of this precursor in the formation of several Pd(II) complexes, including phosphine and diimine-ligated oxidative addition complexes, and in high-turnover-number catalysis of C–O, Suzuki, and Heck coupling reactions.