Pd-PEPPSI: A General Pd-NHC Precatalyst for Suzuki-Miyaura Cross-Coupling of Esters by C-O Cleavage

The Suzuki-Miyaura cross-coupling of aryl esters by selective C-O bond cleavage represents a powerful methodology in organic synthesis. Here, we report that versatile, easily prepared, well-defined Pd-PEPPSI type precatalysts serve as highly reactive catalysts for the direct Suzuki Miyaura cross-coupling of esters. Sterically and electronically diverse aryl esters couple with arylboronic acids in good to excellent yields using a single, operationally simple protocol. Kinetic studies demonstrate that the cross-coupling of aryl esters proceeds with rates similar to the cross coupling of amides. This study strongly supports the use of well-defined Pd(II)-NHC precatalysts bearing pyridine "throw-away" ligands for the selective C(acyl) cleavage of bench-stable carboxylic acid derivatives. Considering the modular scaffold of Pd-NHC precatalysts, we envision that the method will be of general interest for the development of new catalysts for C-O cleavage reactions.