Mechanistic Study of Suzuki-Miyaura Cross-Coupling Reactions of Amides Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

Guangchen Li, Peng Lei, Michal Szostak, Eric Casals-Cruañas, albert poater, Luigi Cavallo, Steven P. Nolan

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

We report a combined experimental and computational investigation of the Suzuki–Miyaura cross-coupling of amides enabled by [Pd(NHC)(allyl)Cl] precatalysts. Most crucially, mechanistic details pertaining to the Pd/NHC catalytic cycle were elucidated by computational methods. Mechanistic insights shed light on the role of each ligand about the metal. Sterics play a key role in the initial activation of the catalyst. As a key insight, we have shown that water participates in the activation of the Pd-NHC catalytic system. Easier activation has led to effect room temperature cross-coupling of a broad range of amides through selective N−C bond scission under the mildest conditions reported to date. The use of sterically hindered [Pd(IPr*)(cin)Cl] reported herein for the first time in the amide cross-coupling indicates that increasing flexible steric bulk of the isopropyl wingtip groups of the NHC ligand provides a modular scaffold for promoting amide cross-coupling in high yields. The precatalytic pathway involving both NHC ligands as well as the catalytic cycle beginning from the Pd species are discussed. The mechanistic details provide insight into the amide bond twist (distortion) that leads to N−C cross-coupling reactions and is required for the efficient N−C bond activation.
Original languageEnglish (US)
Pages (from-to)3096-3106
Number of pages11
JournalChemCatChem
Volume10
Issue number14
DOIs
StatePublished - May 16 2018

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OSR-2015-CCF-1974-03
Acknowledgements: A.P. thanks the Spanish MINECO for a project CTQ2014-59832-JIN, and EU for a FEDER fund (UNGI08-4E-003). Rutgers University and the NSF (CAREER CHE-1650766) are gratefully acknowledged for support (M.S.). The Bruker 500 MHz spectrometer was supported by the NSF-MRI grant (CHE-1229030). P.L. thanks the China Scholarship Council for a fellowship (No. 201606350069). SPN thanks the ERC, King Saud University and King Abdullah University of Science and Technology (Award No. OSR-2015-CCF-1974-03) for support.

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