Pd-PEPPSI: Water-Assisted Suzuki-Miyaura Cross-Coupling of Aryl Esters at Room Temperature using a Practical Palladium-NHC (NHC=N-Heterocyclic Carbene) Precatalyst

A Pd-PEPPSI-catalyzed (Pd=Palladium, PEPPSI=pyridine-enhanced precatalyst preparation stabilization and initiation) Suzuki-Miyaura cross-coupling of aryl esters via selective C-O cleavage at room temperature is reported. The developed catalyst system displays broad substrate scope with respect to both components under practical ambient reaction conditions using readily-available, cheap, modular, air- and moisture-stable Pd-NHC precatalyst (NHC=N-heterocyclic carbene). The use of water proved crucial for achieving high reactivity in this coupling. The catalyst system represents the mildest conditions for the Suzuki-Miyaura cross-coupling of aryl esters reported to date. The protocol also allowed for achieving TON >1,000 (TON=turnover number) in the Suzuki-Miyaura ester coupling for the first time.