Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts
AuthorsMeconi, Giulia Magi
Vummaleti, Sai V. C.
Luque-Urrutia, Jesús Antonio
Nolan, Steven P.
KAUST DepartmentKAUST Catalysis Center (KCC)
KAUST Grant NumberOSR-2015-CCF-1974-03
MetadataShow full item record
AbstractDensity functional theory calculations have been used to investigate the activation mechanism for the precatalyst series [Pd]-X-1–4 derived from [Pd(IPr)(R-allyl)X] species by substitutions at the terminal position of the allyl moiety ([Pd] = Pd(IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a solvent. Our theoretical findings predict an upper barrier trend, corresponding to the activation mechanism for the [Pd]-Cl-1–4 series, in good agreement with the experiments. They indeed provide a quantitative explanation of the low yield (12%) displayed by [Pd]-Cl-1 species (ΔG⧧ ≈ 30.0 kcal/mol) and of the high yields (≈90%) observed in the case of [Pd]-Cl-2–4 complexes (ΔG⧧ ≈ 20.0 kcal/mol). Additionally, the studied Suzuki–Miyaura reaction involving the IPr-Pd(0) species is calculated to be thermodynamically favorable and kinetically facile. Similar investigations for the [Pd]-Br-1–4 series, derived from [Pd(IPr)(R-allyl)Br], indicate that the oxidative addition step for IPr-Pd(0)-mediated catalysis with 4-bromotoluene is kinetically more favored than that with 4-chlorotoluene. Finally, we have explored the potential of Ni-based complexes [Ni((IPr)(R-allyl)X] (X = Cl, Br) as Suzuki–Miyaura reaction catalysts. Apart from a less endergonic reaction energy profile for both precatalyst activation and catalytic cycle, a steep increase in the predicted upper energy barriers (by 2.0–15.0 kcal/mol) is calculated in the activation mechanism for the [Ni]-X-1–4 series compared to the [Pd]-X-1–4 series. Overall, these results suggest that Ni-based precatalysts are expected to be less active than the Pd-based precatalysts for the studied Suzuki–Miyaura reaction.
CitationMeconi GM, Vummaleti SVC, Luque-Urrutia JA, Belanzoni P, Nolan SP, et al. (2017) Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts. Organometallics 36: 2088–2095. Available: http://dx.doi.org/10.1021/acs.organomet.7b00114.
SponsorsA.P. thanks the Spanish MINECO for a project CTQ2014-59832-JIN. M.S. thanks EU for a FEDER fund (UNGI08-4E-003), the Generalitat de Catalunya for project 2014SGR931 and ICREA Academia 2014 prize, and MINECO of Spain through project CTQ2014-54306-P. G.M.M. thanks LLP/Erasmus Student Placement Programme (A.A. 2012/2013) for funding. S.P.N. acknowledges the ERC for support of this work. This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2015-CCF-1974-03. We thank the referees for helpful comments and suggestions.
PublisherAmerican Chemical Society (ACS)