The Pd-NHC-catalyzed acyl-type Buchwald-Hartwig cross-coupling of amides by N-C(O) cleavage (transamidation) provides a valuable alternative to the classical methods for amide synthesis. Herein, we report a combined experimental and computational study of the Buchwald-Hartwig cross-coupling of amides using well-defined, air- and moisture-stable [Pd(NHC)(allyl)Cl] precatalysts. Most crucially, we present a comprehensive evaluation of a series of distinct Pd(ii)-NHC precatalysts featuring different NHC scaffolds and throw-away ligands for the synthesis of functionalized amides that are not compatible with stoichiometric transition-metal-free transamidation methods. Furthermore, we present evaluation of the catalytic cycle by DFT methods for a series of different Pd(ii)-NHC precatalysts. The viability of accessing NHC-supported acyl-palladium(ii) amido complexes will have implications for the design and development of cross-coupling methods involving stable amide electrophiles.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Rutgers University and the NSF (CAREER CHE-1650766) are acknowledged for support. The 500 MHz spectrometer used in this study was supported by the NSF-MRI grant (CHE1229030). A. P. is a Serra Húnter Fellow and ICREA Academia 2019, and thanks the Spanish MINECO for a project PGC2018-097722-B-I00, and European Fund for Regional Development (FEDER) grant UNGI10-4E-801.